Display both master(HEAD) and master(base) options in the merge request comparisons dropdown
Currently, we have the following values in the merge request comparisons dropdown:
In order to support the first iteration of #27008 (closed) we need to display both options for base and HEAD:
The master (HEAD)
option is effectively a link to the diffs with diff_head=true
param: http://127.0.0.1:3000/root/private/-/merge_requests/3/diffs?diff_head=true