'Feature branches' tab should include links to each branch (BB-6913)

The 'Commits' > 'Feature branches' tab list various branches, but the branch names aren't hyperlinked to the branch commit history page (as the 'All commits' page does) - i.e., to:

https://bitbucket.org/AC/REPO/commits/all/tip/BRANCH

Would be useful and presumably simple to add this link.

I'd further suggest a 'Branches' tab within 'Commits', also hyperlinked to the commit history for each? This could give an overview of available branches, last commit comment and date, etc, similar to "git branch -v".