Add deployment approver settings to API

See merge request https://gitlab.com/gitlab-org/gitlab/-/merge_requests/111747



Merged-by: Ahmed Hemdan <ahemdan@gitlab.com>
Approved-by: Ottilia Westerlund <owesterlund@gitlab.com>
Approved-by: Ahmed Hemdan <ahemdan@gitlab.com>
Approved-by: Sincheol (David) Kim <dkim@gitlab.com>
Reviewed-by: Martin Tan <lmtan@jihulab.com>
Reviewed-by: Ahmed Hemdan <ahemdan@gitlab.com>
Co-authored-by: 路小鹿 <1551755561@qq.com>