Add Matching Branches to Code Owner Approval

This is related to MR #13251 (comment 216702309)

Implement design addition to Code Owner Approval based on discussion with @mvanremmerden

In certain cases, there was helpful information (number of matching branches if the selection contains a wildcard and a notice if a branch was removed) in the Last commit section that we removed from the Protected branches. I created an updated version of the design that now brings this back:

Initial mockup	Update