add filtering / searching, sorting to the WebsiteContent listing UI page

[alicewriteswrongs]

As a course author, I'd like to navigate to something specific. Right now once you have more than 20 or so resources that becomes very difficult! You have to just page through until you find it.

Designs and Mockups

UI can be very similar to the filter on /sites

Acceptance Criteria:

• we should add some predictable sort order and some controls (MRU, LRU, Created ascending/descending, alphabetical, others?)
• we should add a filter input (like we have on /sites) which searches the website content items and makes it easy to navigate to them. Should we support some type of full text support? Title matching might be good enough to start.

[alicewriteswrongs]

A good deal of this is already done, the only thing remaining would be the sort order if we wanted to add that.