Highlight the current user's branches in the Branches page

Original Proposal

### Description

1. It would be useful to be able to filter your branches.
2. Highlighting and ordering your branches at the top of the list could also be nice.

Proposal

1. Filter your branches	2. Highlight your branches

Proposal nav-links, nav-text and other options should follow gitlab-ce!15402.

Proposal

Highlighting the current user's branches to make them easily discoverable when the user is scanning the list.

Design

• master, or whichever the default branch is, appears at the top of the list followed by the user's branches.
• Use #F6FAFD as the background-color.
• Add left and right padding of 16px for all the list items.
• We can retain the sorting order for the Overview page. But for the rest of the pages, the default branch should appear on top of the list followed by the rest of the branches as per the currently selected sort order. The highlighted branches can mix with the rest i.e they should follow the sort order. The default branch appearing on top should be the only exception to the sort order.
• The above changes applies to Active, Stale and All pages. The Overview page list items already have left and right paddings.

Links / references

This would be a nice extension to gitlab-ce#17293.