[ty] Improve specialization-error diagnostics (#20326)

## Summary

Add information about the upper bound or the constraints of the type
variable to the `SpecializationError` diagnostics.

crates/ty_python_semantic/resources/mdtest/diagnostics/union_call.md

@@ -112,7 +112,7 @@ def _(n: int):
     # error: [too-many-positional-arguments]
     # error: [invalid-argument-type] "Argument to function `f2` is incorrect: Expected `str`, found `Literal[3]`"
     # error: [missing-argument]
-    # error: [invalid-argument-type] "Argument to function `f4` is incorrect: Argument type `Literal[3]` does not satisfy upper bound of type variable `T`"
+    # error: [invalid-argument-type] "Argument to function `f4` is incorrect: Argument type `Literal[3]` does not satisfy upper bound `str` of type variable `T`"
     # error: [invalid-argument-type] "Argument to function `f5` is incorrect: Expected `str`, found `Literal[3]`"
     # error: [no-matching-overload] "No overload of function `f6` matches arguments"
     # error: [call-non-callable] "Object of type `Literal[5]` is not callable"

crates/ty_python_semantic/resources/mdtest/snapshots/functions.md_-_Generic_functions___L…_-_Inferring_a_bound_ty…_(d50204b9d91b7bd1).snap

@@ -74,7 +74,7 @@ error[invalid-argument-type]: Argument to function `f` is incorrect
 10 | reveal_type(f(True))  # revealed: Literal[True]
 11 | # error: [invalid-argument-type]
 12 | reveal_type(f("string"))  # revealed: Unknown
-   |               ^^^^^^^^ Argument type `Literal["string"]` does not satisfy upper bound of type variable `T`
+   |               ^^^^^^^^ Argument type `Literal["string"]` does not satisfy upper bound `int` of type variable `T`
    |
 info: Type variable defined here
  --> src/mdtest_snippet.py:4:1

crates/ty_python_semantic/resources/mdtest/snapshots/functions.md_-_Generic_functions___L…_-_Inferring_a_constrai…_(48ab83f977c109b4).snap

@@ -89,7 +89,7 @@ error[invalid-argument-type]: Argument to function `f` is incorrect
 11 | reveal_type(f(None))  # revealed: None
 12 | # error: [invalid-argument-type]
 13 | reveal_type(f("string"))  # revealed: Unknown
-   |               ^^^^^^^^ Argument type `Literal["string"]` does not satisfy constraints of type variable `T`
+   |               ^^^^^^^^ Argument type `Literal["string"]` does not satisfy constraints (`int`, `None`) of type variable `T`
    |
 info: Type variable defined here
  --> src/mdtest_snippet.py:4:1

crates/ty_python_semantic/resources/mdtest/snapshots/functions.md_-_Generic_functions___P…_-_Inferring_a_bound_ty…_(5935d14c26afe407).snap

@@ -71,7 +71,7 @@ error[invalid-argument-type]: Argument to function `f` is incorrect
 7 | reveal_type(f(True))  # revealed: Literal[True]
 8 | # error: [invalid-argument-type]
 9 | reveal_type(f("string"))  # revealed: Unknown
-  |               ^^^^^^^^ Argument type `Literal["string"]` does not satisfy upper bound of type variable `T`
+  |               ^^^^^^^^ Argument type `Literal["string"]` does not satisfy upper bound `int` of type variable `T`
   |
 info: Type variable defined here
  --> src/mdtest_snippet.py:3:7

crates/ty_python_semantic/resources/mdtest/snapshots/functions.md_-_Generic_functions___P…_-_Inferring_a_constrai…_(d2c475fccc70a8e2).snap

@@ -86,7 +86,7 @@ error[invalid-argument-type]: Argument to function `f` is incorrect
  8 | reveal_type(f(None))  # revealed: None
  9 | # error: [invalid-argument-type]
 10 | reveal_type(f("string"))  # revealed: Unknown
-   |               ^^^^^^^^ Argument type `Literal["string"]` does not satisfy constraints of type variable `T`
+   |               ^^^^^^^^ Argument type `Literal["string"]` does not satisfy constraints (`int`, `None`) of type variable `T`
    |
 info: Type variable defined here
  --> src/mdtest_snippet.py:3:7

crates/ty_python_semantic/resources/mdtest/snapshots/union_call.md_-_Calling_a_union_of_f…_-_Try_to_cover_all_pos…_-_Cover_non-keyword_re…_(707b284610419a54).snap

@@ -66,7 +66,7 @@ mdtest path: crates/ty_python_semantic/resources/mdtest/diagnostics/union_call.m
 52 |     # error: [too-many-positional-arguments]
 53 |     # error: [invalid-argument-type] "Argument to function `f2` is incorrect: Expected `str`, found `Literal[3]`"
 54 |     # error: [missing-argument]
-55 |     # error: [invalid-argument-type] "Argument to function `f4` is incorrect: Argument type `Literal[3]` does not satisfy upper bound of type variable `T`"
+55 |     # error: [invalid-argument-type] "Argument to function `f4` is incorrect: Argument type `Literal[3]` does not satisfy upper bound `str` of type variable `T`"
 56 |     # error: [invalid-argument-type] "Argument to function `f5` is incorrect: Expected `str`, found `Literal[3]`"
 57 |     # error: [no-matching-overload] "No overload of function `f6` matches arguments"
 58 |     # error: [call-non-callable] "Object of type `Literal[5]` is not callable"
@@ -188,7 +188,7 @@ error[invalid-argument-type]: Argument to function `f4` is incorrect
 58 |     # error: [call-non-callable] "Object of type `Literal[5]` is not callable"
 59 |     # error: [call-non-callable] "Object of type `PossiblyNotCallable` is not callable (possibly unbound `__call__` method)"
 60 |     x = f(3)
-   |           ^ Argument type `Literal[3]` does not satisfy upper bound of type variable `T`
+   |           ^ Argument type `Literal[3]` does not satisfy upper bound `str` of type variable `T`
    |
 info: Type variable defined here
   --> src/mdtest_snippet.py:13:8

crates/ty_python_semantic/src/types/call/bind.rs

@@ -3086,14 +3086,20 @@ impl<'db> BindingError<'db> {
                         String::new()
                     }
                 ));
-                diag.set_primary_message(format_args!(
-                    "Argument type `{argument_ty_display}` does not satisfy {} of type variable `{}`",
-                    match error {
-                        SpecializationError::MismatchedBound {..} => "upper bound",
-                        SpecializationError::MismatchedConstraint {..} => "constraints",
-                    },
-                    typevar.name(context.db()),
-                ));
+
+                let typevar_name = typevar.name(context.db());
+                match error {
+                    SpecializationError::MismatchedBound { .. } => {
+                        diag.set_primary_message(format_args!("Argument type `{argument_ty_display}` does not satisfy upper bound `{}` of type variable `{typevar_name}`",
+                        typevar.upper_bound(context.db()).expect("type variable should have an upper bound if this error occurs").display(context.db())
+                    ));
+                    }
+                    SpecializationError::MismatchedConstraint { .. } => {
+                        diag.set_primary_message(format_args!("Argument type `{argument_ty_display}` does not satisfy constraints ({}) of type variable `{typevar_name}`",
+                        typevar.constraints(context.db()).expect("type variable should have constraints if this error occurs").iter().map(|ty| format!("`{}`", ty.display(context.db()))).join(", ")
+                    ));
+                    }
+                }
 
                 if let Some(typevar_definition) = typevar.definition(context.db()) {
                     let module = parsed_module(context.db(), typevar_definition.file(context.db()))