Update the merge request widget's "Merge" button to support merge trains
What does this MR do?
Updates the Merge
button in the merge request widget to support merge trains:
This feature is effectively hidden behind the merge_trains
feature flag.
This is one step towards the merge trains feature described in https://gitlab.com/gitlab-org/gitlab-ee/issues/9186.
UX specs: https://balsamiq.cloud/saotw6e/pjtd1bw/rED67
CE backport: https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/27594
Edited by Nathan Friend