Combine OldDiagnostic and Diagnostic (#19053)

## Summary

This PR is a collaboration with @AlexWaygood from our pairing session
last Friday.

The main goal here is removing `ruff_linter::message::OldDiagnostic` in
favor of
using `ruff_db::diagnostic::Diagnostic` directly. This involved a few
major steps:

- Transferring the fields
- Transferring the methods and trait implementations, where possible
- Converting some constructor methods to free functions
- Moving the `SecondaryCode` struct
- Updating the method names

I'm hoping that some of the methods, especially those in the
`expect_ruff_*`
family, won't be necessary long-term, but I avoided trying to replace
them
entirely for now to keep the already-large diff a bit smaller.

### Related refactors

Alex and I noticed a few refactoring opportunities while looking at the
code,
specifically the very similar implementations for
`create_parse_diagnostic`,
`create_unsupported_syntax_diagnostic`, and
`create_semantic_syntax_diagnostic`.
We combined these into a single generic function, which I then copied
into
`ruff_linter::message` with some small changes and a TODO to combine
them in the
future.

I also deleted the `DisplayParseErrorType` and `TruncateAtNewline` types
for
reporting parse errors. These were added in #4124, I believe to work
around the
error messages from LALRPOP. Removing these didn't affect any tests, so
I think
they were unnecessary now that we fully control the error messages from
the
parser.

On a more minor note, I factored out some calls to the
`OldDiagnostic::filename`
(now `Diagnostic::expect_ruff_filename`) function to avoid repeatedly
allocating
`String`s in some places.

### Snapshot changes

The `show_statistics_syntax_errors` integration test changed because the
`OldDiagnostic::name` method used `syntax-error` instead of
`invalid-syntax`
like in ty. I think this (`--statistics`) is one of the only places we
actually
use this name for syntax errors, so I hope this is okay. An alternative
is to
use `syntax-error` in ty too.

The other snapshot changes are from removing this code, as discussed on

[Discord](1388252408):


34052a1185/crates/ruff_linter/src/message/mod.rs (L128-L135)

I think both of these are technically breaking changes, but they only
affect
syntax errors and are very narrow in scope, while also pretty
substantially
simplifying the refactor, so I hope they're okay to include in a patch
release.

## Test plan

Existing tests, with the adjustments mentioned above

---------

Co-authored-by: Alex Waygood <Alex.Waygood@Gmail.com>

crates/ruff_server/Cargo.toml

@@ -13,6 +13,7 @@ license = { workspace = true }
 [lib]
 
 [dependencies]
+ruff_db = { workspace = true }
 ruff_diagnostics = { workspace = true }
 ruff_formatter = { workspace = true }
 ruff_linter = { workspace = true }

crates/ruff_server/src/lint.rs

@@ -9,13 +9,13 @@ use crate::{
     resolve::is_document_excluded_for_linting,
     session::DocumentQuery,
 };
+use ruff_db::diagnostic::Diagnostic;
 use ruff_diagnostics::{Applicability, Edit, Fix};
 use ruff_linter::{
     Locator,
     directives::{Flags, extract_directives},
     generate_noqa_edits,
     linter::check_path,
-    message::OldDiagnostic,
     package::PackageRoot,
     packaging::detect_package_root,
     settings::flags,
@@ -228,13 +228,13 @@ pub(crate) fn fixes_for_diagnostics(
 /// Generates an LSP diagnostic with an associated cell index for the diagnostic to go in.
 /// If the source kind is a text document, the cell index will always be `0`.
 fn to_lsp_diagnostic(
-    diagnostic: &OldDiagnostic,
+    diagnostic: &Diagnostic,
     noqa_edit: Option<Edit>,
     source_kind: &SourceKind,
     index: &LineIndex,
     encoding: PositionEncoding,
 ) -> (usize, lsp_types::Diagnostic) {
-    let diagnostic_range = diagnostic.range();
+    let diagnostic_range = diagnostic.expect_range();
     let name = diagnostic.name();
     let body = diagnostic.body().to_string();
     let fix = diagnostic.fix();