Tag files manually

The Mac file picker has an option to apply tags to newly-saved files.
There is a mechanism to automatically apply the tags to the files, but
that mechanism is not reliable. Therefore, plumb tag information
throughout Chromium and do it ourselves.

Fixed: 1510399
Change-Id: Ib3aae475f019937498d167519e10f5a522cf65b6
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/5217354
Reviewed-by: danakj <danakj@chromium.org>
Reviewed-by: Mark Mentovai <mark@chromium.org>
Reviewed-by: Min Qin <qinmin@chromium.org>
Commit-Queue: Avi Drissman <avi@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1250445}