Implement UI favorites

[suecarmol]

Description

Implement the UI for the collection favoriting system:

• Add a Favorites tab
• Add a star to add collections to favorites
• Add view that works asynchronously to favorite a collection

Rationale

Favoriting collections is a highly requested feature for the Library.

Phabricator Ticket

T285671

How Has This Been Tested?

Tested manually

Screenshots of your changes (if appropriate):

Types of changes

What types of changes does your code introduce? Add an x in all the boxes that apply:

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• Minor change (fix a typo, add a translation tag, add section to README, etc.)

[jsnshrmn]

Looks great! I manually tested this emulating a few different mobile devices, and found that it worked as expected. In the interest of expediency, I'm going to go ahead and merge this in, even though it could use unit tests.