Move full diagnostic rendering to ruff_db (#19415)

## Summary

This PR switches the `full` output format in Ruff over to use the
rendering code
in `ruff_db`. As proposed in the design doc, this involves a lot of
changes to the snapshot output.

I also had to comment out this assertion with a TODO to replace it after
https://github.com/astral-sh/ruff/issues/19688 because many of Ruff's
"file-level" annotations aren't actually file-level. They just happen to
occur at the start of the file, especially in tests with very short
snippets.


529d81daca/crates/ruff_annotate_snippets/src/renderer/display_list.rs (L1204-L1208)

I broke up the snapshot commits at the end into several blocks, but I
don't think it's enough to help with review. The first few (notebooks,
syntax errors, and test rules) are small enough to look at, but I
couldn't really think of other categories beyond that. I'm happy to
break those up or pick out specific examples beyond what I have below,
if that would help.

The minimal code changes are in this
[range](abd28f1e77),
with the snapshot commits following. Moving the `FullRenderer` and
updating the `EmitterFlags` aren't strictly necessary either. I even
dropped the renderer commit this morning but figured it made sense to
keep it since we have the `full` module for tests. I don't feel strongly
either way.

## Test Plan

I did actually click through all 1700 snapshots individually instead of
accepting them all at once, although I moved through them quickly. There
are a
few main categories:

### Lint diagnostics

```diff
-unused.py:8:19: F401 [*] `pathlib` imported but unused
+F401 [*] `pathlib` imported but unused
+  --> unused.py:8:19
    |
  7 | # Unused, _not_ marked as required (due to the alias).
  8 | import pathlib as non_alias
-   |                   ^^^^^^^^^ F401
+   |                   ^^^^^^^^^
  9 |
 10 | # Unused, marked as required.
    |
-   = help: Remove unused import: `pathlib`
+help: Remove unused import: `pathlib`
```

- The filename and line numbers are moved to the second line
- The second noqa code next to the underline is removed

### Syntax errors

These are much like the above.

```diff
-    -:1:16: invalid-syntax: Expected one or more symbol names after import
+    invalid-syntax: Expected one or more symbol names after import
+     --> -:1:16
       |
     1 | from foo import
       |                ^
```

One thing I noticed while reviewing some of these, but I don't think is
strictly syntax-error-related, is that some of the new diagnostics have
a little less context after the error. I don't think this is a problem,
but it's one small discrepancy I hadn't noticed before. Here's a minor
example:

```diff
-syntax_errors.py:1:15: invalid-syntax: Expected one or more symbol names after import
+invalid-syntax: Expected one or more symbol names after import
+ --> syntax_errors.py:1:15
   |
 1 | from os import
   |               ^
 2 |
 3 | if call(foo
-4 |     def bar():
   |
```

And one of the biggest examples:

```diff
-E30_syntax_error.py:18:11: invalid-syntax: Expected ')', found newline
+invalid-syntax: Expected ')', found newline
+  --> E30_syntax_error.py:18:11
    |
 16 |         pass
 17 |
 18 | foo = Foo(
    |           ^
-19 |
-20 |
-21 | def top(
    |
```

Similarly, a few of the lint diagnostics showed that the cut indicator
calculation for overly long lines is also slightly different, but I
think that's okay too.

### Full-file diagnostics

```diff
-comment.py:1:1: I002 [*] Missing required import: `from __future__ import annotations`
+I002 [*] Missing required import: `from __future__ import annotations`
+--> comment.py:1:1
+help: Insert required import: `from __future__ import annotations`
+
```

As noted above, these will be much more rare after #19688 too. This case
isn't a true full-file diagnostic and will render a snippet in the
future, but you can see that we're now rendering the help message that
would have been discarded before. In contrast, this is a true full-file
diagnostic and should still look like this after #19688:

```diff
-__init__.py:1:1: A005 Module `logging` shadows a Python standard-library module
+A005 Module `logging` shadows a Python standard-library module
+--> __init__.py:1:1
```

### Jupyter notebooks

There's nothing particularly different about these, just showing off the
cell index again.

```diff
-    Jupyter.ipynb:cell 3:1:7: F821 Undefined name `x`
+    F821 Undefined name `x`
+     --> Jupyter.ipynb:cell 3:1:7
       |
     1 | print(x)
-      |       ^ F821
+      |       ^
       |
```

crates/ruff_annotate_snippets/src/renderer/display_list.rs

@@ -1201,11 +1201,16 @@ fn format_snippet<'m>(
 
     let is_file_level = snippet.annotations.iter().any(|ann| ann.is_file_level);
     if is_file_level {
-        assert!(
-            snippet.source.is_empty(),
-            "Non-empty file-level snippet that won't be rendered: {:?}",
-            snippet.source
-        );
+        // TODO(brent) enable this assertion again once we set `is_file_level` for individual rules.
+        // It's causing too many false positives currently when the default is to make any
+        // annotation with a default range file-level. See
+        // https://github.com/astral-sh/ruff/issues/19688.
+        //
+        // assert!(
+        //     snippet.source.is_empty(),
+        //     "Non-empty file-level snippet that won't be rendered: {:?}",
+        //     snippet.source
+        // );
         let header = format_header(origin, main_range, &[], is_first, snippet.cell_index);
         return DisplaySet {
             display_lines: header.map_or_else(Vec::new, |header| vec![header]),