red_knot_python_semantic: migrate types/infer to new diagnostic model

I gave up trying to do this one lint at a time and just (mostly)
mechanically translated this entire file in one go.

Generally the messages stay the same (with most moving from an
annotation message to the diagnostic's main message). I added a couple
of `info` sub-diagnostics where it seemed to be the obvious intent.

crates/red_knot_python_semantic/resources/mdtest/snapshots/attribute_assignment.md_-_Attribute_assignment_-_Pure_instance_attributes.snap

@@ -40,13 +40,13 @@ error: lint:invalid-assignment: Object of type `Literal["wrong"]` is not assigna
 ```
 
 ```
-error: lint:invalid-attribute-access
+error: lint:invalid-attribute-access: Cannot assign to instance attribute `attr` from the class object `Literal[C]`
  --> /src/mdtest_snippet.py:9:1
   |
 7 | instance.attr = "wrong"  # error: [invalid-assignment]
 8 |
 9 | C.attr = 1  # error: [invalid-attribute-access]
-  | ^^^^^^ Cannot assign to instance attribute `attr` from the class object `Literal[C]`
+  | ^^^^^^
   |
 
 ```

crates/red_knot_python_semantic/resources/mdtest/snapshots/attribute_assignment.md_-_Attribute_assignment_-_Unknown_attributes.snap

@@ -23,13 +23,13 @@ mdtest path: crates/red_knot_python_semantic/resources/mdtest/diagnostics/attrib
 # Diagnostics
 
 ```
-error: lint:unresolved-attribute
+error: lint:unresolved-attribute: Unresolved attribute `non_existent` on type `Literal[C]`.
  --> /src/mdtest_snippet.py:3:1
   |
 1 | class C: ...
 2 |
 3 | C.non_existent = 1  # error: [unresolved-attribute]
-  | ^^^^^^^^^^^^^^ Unresolved attribute `non_existent` on type `Literal[C]`.
+  | ^^^^^^^^^^^^^^
 4 |
 5 | instance = C()
   |
@@ -37,12 +37,12 @@ error: lint:unresolved-attribute
 ```
 
 ```
-error: lint:unresolved-attribute
+error: lint:unresolved-attribute: Unresolved attribute `non_existent` on type `C`.
  --> /src/mdtest_snippet.py:6:1
   |
 5 | instance = C()
 6 | instance.non_existent = 1  # error: [unresolved-attribute]
-  | ^^^^^^^^^^^^^^^^^^^^^ Unresolved attribute `non_existent` on type `C`.
+  | ^^^^^^^^^^^^^^^^^^^^^
   |
 
 ```

crates/red_knot_python_semantic/resources/mdtest/snapshots/attribute_assignment.md_-_Attribute_assignment_-_`ClassVar`s.snap

@@ -40,12 +40,12 @@ error: lint:invalid-assignment: Object of type `Literal["wrong"]` is not assigna
 ```
 
 ```
-error: lint:invalid-attribute-access
+error: lint:invalid-attribute-access: Cannot assign to ClassVar `attr` from an instance of type `C`
   --> /src/mdtest_snippet.py:10:1
    |
  9 | instance = C()
 10 | instance.attr = 1  # error: [invalid-attribute-access]
-   | ^^^^^^^^^^^^^ Cannot assign to ClassVar `attr` from an instance of type `C`
+   | ^^^^^^^^^^^^^
    |
 
 ```

crates/red_knot_python_semantic/resources/mdtest/snapshots/basic.md_-_Structures_-_Unresolvable_module_import.snap

@@ -18,11 +18,11 @@ mdtest path: crates/red_knot_python_semantic/resources/mdtest/import/basic.md
 # Diagnostics
 
 ```
-error: lint:unresolved-import
+error: lint:unresolved-import: Cannot resolve import `zqzqzqzqzqzqzq`
  --> /src/mdtest_snippet.py:1:8
   |
 1 | import zqzqzqzqzqzqzq  # error: [unresolved-import] "Cannot resolve import `zqzqzqzqzqzqzq`"
-  |        ^^^^^^^^^^^^^^ Cannot resolve import `zqzqzqzqzqzqzq`
+  |        ^^^^^^^^^^^^^^
   |
 
 ```

crates/red_knot_python_semantic/resources/mdtest/snapshots/basic.md_-_Structures_-_Unresolvable_submodule_imports.snap

@@ -27,12 +27,12 @@ mdtest path: crates/red_knot_python_semantic/resources/mdtest/import/basic.md
 # Diagnostics
 
 ```
-error: lint:unresolved-import
+error: lint:unresolved-import: Cannot resolve import `a.foo`
  --> /src/mdtest_snippet.py:2:8
   |
 1 | # Topmost component resolvable, submodule not resolvable:
 2 | import a.foo  # error: [unresolved-import] "Cannot resolve import `a.foo`"
-  |        ^^^^^ Cannot resolve import `a.foo`
+  |        ^^^^^
 3 |
 4 | # Topmost component unresolvable:
   |
@@ -40,12 +40,12 @@ error: lint:unresolved-import
 ```
 
 ```
-error: lint:unresolved-import
+error: lint:unresolved-import: Cannot resolve import `b.foo`
  --> /src/mdtest_snippet.py:5:8
   |
 4 | # Topmost component unresolvable:
 5 | import b.foo  # error: [unresolved-import] "Cannot resolve import `b.foo`"
-  |        ^^^^^ Cannot resolve import `b.foo`
+  |        ^^^^^
   |
 
 ```

crates/red_knot_python_semantic/resources/mdtest/snapshots/unresolved_import.md_-_Unresolved_import_diagnostics_-_An_unresolvable_import_that_does_not_use_`from`.snap

@@ -20,11 +20,11 @@ mdtest path: crates/red_knot_python_semantic/resources/mdtest/diagnostics/unreso
 # Diagnostics
 
 ```
-error: lint:unresolved-import
+error: lint:unresolved-import: Cannot resolve import `does_not_exist`
  --> /src/mdtest_snippet.py:1:8
   |
 1 | import does_not_exist  # error: [unresolved-import]
-  |        ^^^^^^^^^^^^^^ Cannot resolve import `does_not_exist`
+  |        ^^^^^^^^^^^^^^
 2 |
 3 | x = does_not_exist.foo
   |

crates/red_knot_python_semantic/resources/mdtest/snapshots/unresolved_import.md_-_Unresolved_import_diagnostics_-_Using_`from`_with_a_resolvable_module_but_unresolvable_item.snap

@@ -25,11 +25,11 @@ mdtest path: crates/red_knot_python_semantic/resources/mdtest/diagnostics/unreso
 # Diagnostics
 
 ```
-error: lint:unresolved-import
+error: lint:unresolved-import: Module `a` has no member `does_not_exist`
  --> /src/mdtest_snippet.py:1:28
   |
 1 | from a import does_exist1, does_not_exist, does_exist2  # error: [unresolved-import]
-  |                            ^^^^^^^^^^^^^^ Module `a` has no member `does_not_exist`
+  |                            ^^^^^^^^^^^^^^
   |
 
 ```

crates/red_knot_python_semantic/resources/mdtest/snapshots/unresolved_import.md_-_Unresolved_import_diagnostics_-_Using_`from`_with_an_unknown_current_module.snap

@@ -20,11 +20,11 @@ mdtest path: crates/red_knot_python_semantic/resources/mdtest/diagnostics/unreso
 # Diagnostics
 
 ```
-error: lint:unresolved-import
+error: lint:unresolved-import: Cannot resolve import `.does_not_exist`
  --> /src/mdtest_snippet.py:1:7
   |
 1 | from .does_not_exist import add  # error: [unresolved-import]
-  |       ^^^^^^^^^^^^^^ Cannot resolve import `.does_not_exist`
+  |       ^^^^^^^^^^^^^^
 2 |
 3 | stat = add(10, 15)
   |

crates/red_knot_python_semantic/resources/mdtest/snapshots/unresolved_import.md_-_Unresolved_import_diagnostics_-_Using_`from`_with_an_unknown_nested_module.snap

@@ -20,11 +20,11 @@ mdtest path: crates/red_knot_python_semantic/resources/mdtest/diagnostics/unreso
 # Diagnostics
 
 ```
-error: lint:unresolved-import
+error: lint:unresolved-import: Cannot resolve import `.does_not_exist.foo.bar`
  --> /src/mdtest_snippet.py:1:7
   |
 1 | from .does_not_exist.foo.bar import add  # error: [unresolved-import]
-  |       ^^^^^^^^^^^^^^^^^^^^^^ Cannot resolve import `.does_not_exist.foo.bar`
+  |       ^^^^^^^^^^^^^^^^^^^^^^
 2 |
 3 | stat = add(10, 15)
   |

crates/red_knot_python_semantic/resources/mdtest/snapshots/unresolved_import.md_-_Unresolved_import_diagnostics_-_Using_`from`_with_an_unresolvable_module.snap

@@ -20,11 +20,11 @@ mdtest path: crates/red_knot_python_semantic/resources/mdtest/diagnostics/unreso
 # Diagnostics
 
 ```
-error: lint:unresolved-import
+error: lint:unresolved-import: Cannot resolve import `does_not_exist`
  --> /src/mdtest_snippet.py:1:6
   |
 1 | from does_not_exist import add  # error: [unresolved-import]
-  |      ^^^^^^^^^^^^^^ Cannot resolve import `does_not_exist`
+  |      ^^^^^^^^^^^^^^
 2 |
 3 | stat = add(10, 15)
   |

crates/red_knot_python_semantic/resources/mdtest/snapshots/unresolved_import.md_-_Unresolved_import_diagnostics_-_Using_`from`_with_too_many_leading_dots.snap

@@ -32,11 +32,11 @@ mdtest path: crates/red_knot_python_semantic/resources/mdtest/diagnostics/unreso
 # Diagnostics
 
 ```
-error: lint:unresolved-import
+error: lint:unresolved-import: Cannot resolve import `....foo`
  --> /src/package/subpackage/subsubpackage/__init__.py:1:10
   |
 1 | from ....foo import add  # error: [unresolved-import]
-  |          ^^^ Cannot resolve import `....foo`
+  |          ^^^
 2 |
 3 | stat = add(10, 15)
   |