Stabilize generated rule code for incremental builds (#25726)
## Summary
I found this while looking at some changes in `rust` itself. `map_codes`
groups rules in a `HashMap` and previously emitted the `Rule::noqa_code`
match arms in hash iteration order. Since that order is randomized
between compiler processes, an unrelated edit could change the generated
function and invalidate a `ruff_linter` codegen unit even when the rule
mapping itself was unchanged!
On main, touching then rebuilding only reused 255 of 256 `ruff_linter`
ThinLTO modules (and recompiled the module containing
`Rule::noqa_code`); with this change, `rustc` reused all 256 modules.
This can make incremental rebuilds ~10-15% faster!
Here's the output of `hyperfine --warmup 3 --runs 10 --prepare 'touch
crates/ruff_linter/src/codes.rs' 'env CARGO_INCREMENTAL=1
CARGO_TARGET_DIR=... cargo build -p ruff_linter'`:
```
Revision Pass 1 Pass 2 Combined mean
━━━━━━━━━━ ━━━━━━━━━━━━━━━━━ ━━━━━━━━━━━━━━━━━ ━━━━━━━━━━━━━━━
HEAD 2.667s ± 0.052s 2.597s ± 0.042s 2.632s
────────── ───────────────── ───────────────── ───────────────
HEAD^ 3.093s ± 0.043s 3.038s ± 0.038s 3.066s
```
