Show first 10 branches, then "More Branches" for commits on huge numbers of branches

Summary: Fixes T9562. We already do this for tags, but didn't have similar logic for branches. Implement that logic.

Test Plan:

• Set limit to 1, saw "More branches", clicked it, got the correct results.
• Verified that branch table with no specified commit still works properly.

Reviewers: chad

Reviewed By: chad

Maniphest Tasks: T9562

Differential Revision: https://secure.phabricator.com/D15284