Add collection page list/search endpoint

[tw4l]

Fixes #2353

Adds a new endpoint to list pages in a collection, with filtering available on url (exact match), ts, urlPrefix, isSeed, and depth, as well as accompanying tests. Additional sort options have been added as well.

These same filters and sort options have also been added to the crawl pages endpoint.

Also fixes an issue where isSeed wasn't being set in the database when false but only added on serialization, which was preventing filtering from working as expected.

[ikreymer]

We should probably do this for crawls as well, so larger crawls can be replayed easily w/o having to be added to collections..

[tw4l]

@ikreymer This is ready for re-review. Changes made:

• isSeed and depth filters and sort options added to both crawl and collection pages endpoints
• Fixed issue where isSeed was being set to false for pages on serialization but kept null in the database, which was preventing filtering from working as expected

The only remaining test failure is the unrelated QA failure.