Create user_group_member_roles when group membership is created/updated
## JTBD - [x] Create service and worker, run background job to create `user_group_member_roles` records for a user when they are added to a group membership (https://gitlab.com/gitlab-org/gitlab/-/merge_requests/195127) - [x] Run background job to update `user_group_member_roles` records of a user when their membership in a group is updated (https://gitlab.com/gitlab-org/gitlab/-/merge_requests/196079)
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