merge_pr_51478

Translator: Implement progress updates

This fully implements reporting the actual progress of both the
TranslateKit and the Language packs to the translator's monitor.

Fixed: 391715395
Change-Id: I6d5f6292781159cc9b22d5f11b8a4bc267cb8145
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/6350513
Reviewed-by: Christine Hollingsworth [email protected]
Reviewed-by: Matthew Denton [email protected]
Reviewed-by: Erik Chen [email protected]
Commit-Queue: Nathan Memmott [email protected]
Cr-Commit-Position: refs/heads/main@{#1435116}