Merge branch '473840-use-semantic-tokens-in-app-assets-stylesheets-framework-common-scss-fwhite-fgray' into 'master' 

Replace fgray with gl-fill-gray-500 and remove fwhite

See merge request https://gitlab.com/gitlab-org/gitlab/-/merge_requests/160471



Merged-by: Paul Slaughter <pslaughter@gitlab.com>
Approved-by: Annabel Dunstone Gray <annabel.dunstone@gmail.com>
Approved-by: Julia Miocene <jmiocene@gitlab.com>
Approved-by: Juliet Wanjohi <jwanjohi@gitlab.com>
Approved-by: Heinrich Lee Yu <heinrich@gitlab.com>
Approved-by: Briley Sandlin <bsandlin@gitlab.com>
Approved-by: Paul Slaughter <pslaughter@gitlab.com>
Co-authored-by: Chad Lavimoniere <clavimoniere@gitlab.com>