Rollup merge of #100379 - davidtwco:triagebot-diag, r=Mark-Simulacrum

triagebot: add translation-related mention groups

- Move some code around so that triagebot can ping relevant parties when translation logic is modified.
- Add mention groups to triagebot for translation-related files/folders.
- Auto-label pull requests with changes to translation-related files/folders with `A-translation`.

r? `@Mark-Simulacrum`

diff --cc compiler/rustc_errors/src/lib.rs
Simple merge