Merge branch '436616/create-audit-event-streamer-classes' into 'master'

Create audit event external streamer classes

See merge request https://gitlab.com/gitlab-org/gitlab/-/merge_requests/171430



Merged-by: Harsimar Sandhu <hsandhu@gitlab.com>
Approved-by: david hamp-gonsalves <dhamp-gonsalves@gitlab.com>
Approved-by: Sarah Yasonik <syasonik@gitlab.com>
Approved-by: Harsimar Sandhu <hsandhu@gitlab.com>
Reviewed-by: Sarah Yasonik <syasonik@gitlab.com>
Co-authored-by: Andrew Jung <ajung@gitlab.com>