Merge branch 'mr-filter' into 'master'

Add "merged" and "requested changes" to MR activity filters

See merge request https://gitlab.com/gitlab-org/gitlab/-/merge_requests/165233



Merged-by: Phil Hughes <me@iamphill.com>
Approved-by: Phil Hughes <me@iamphill.com>
Reviewed-by: Phil Hughes <me@iamphill.com>
Reviewed-by: Annabel Dunstone Gray <annabel.dunstone@gmail.com>
Co-authored-by: Annabel Dunstone Gray <annabel.dunstone@gmail.com>