Merge branch '376864-open_api_applications' into 'master'

Add OpenAPI documentation for applications

See merge request https://gitlab.com/gitlab-org/gitlab/-/merge_requests/102467



Merged-by: Imre Farkas <ifarkas@gitlab.com>
Approved-by: Ian Anderson <ianderson@gitlab.com>
Approved-by: Imre Farkas <ifarkas@gitlab.com>
Co-authored-by: Aboobacker MK <aboobackervyd@gmail.com>