Redesign configuring branch options in a merge request

Currently, to edit branch options associated with a merge request, you have to go to the edit merge request form, and do it there:

This is confusing, because as the person who merges the merge request, you can also make some decisions inline in the widget itself, before merging.

The purpose of this issue is to redesign the UX flow so that you can do this without entering the edit merge request form. For example, is there a way to go into some inline edit mode while in the widget.