Allow sorting by last branch commit

**Is your feature request related to a problem? Please describe.**
I have quite a few branches and can not always remember the name of them.

**Describe the solution you'd like**
It would be amazing if the branch list could be sorted my last-commit date.

**Describe alternatives you've considered**
Don't know of any.

The issue does not name any files, tests, or entry points. Start by locating the branch list and its existing sorting behavior, then inspect how branch last-commit dates are obtained. Done means the branch list can be sorted by last-commit date and the behavior is covered by an appropriate test.

Written by the indexing model from the issue text.