Merge branch '456080-add-visual-indicators-for-imported-merge-requests' into 'master'

Add "Imported" badge to MR header and sticky header

See merge request https://gitlab.com/gitlab-org/gitlab/-/merge_requests/150095



Merged-by: Phil Hughes <me@iamphill.com>
Approved-by: Emily Bauman <ebauman@gitlab.com>
Approved-by: Phil Hughes <me@iamphill.com>
Co-authored-by: Justin Ho Tuan Duong <hduong@gitlab.com>