Merge branch '442371-integrate-bulk-assignment-api' into 'master'

Integrate GitLab Duo Pro bulk add-on assignment API with the UI

See merge request https://gitlab.com/gitlab-org/gitlab/-/merge_requests/147505



Merged-by: Vitaly Slobodin <vslobodin@gitlab.com>
Approved-by: Tim Noah <tnoah@gitlab.com>
Approved-by: Ammar Alakkad <aalakkad@gitlab.com>
Approved-by: Vitaly Slobodin <vslobodin@gitlab.com>
Reviewed-by: Ammar Alakkad <aalakkad@gitlab.com>
Co-authored-by: Vamsi Vempati <vvempati@gitlab.com>