Tell us about your environment

• MarkBind Version: 1.20.0

Rationale: Our current test_site contains 10 pages, and is getting more unwieldy as we add new features to MarkBind that require functional testing. Since we now have the ability to use multiple test sites (#588), we should split up these pages into multiple test sites, as well as consider if the main test page can be split up as well. This will reduce the size of the diffs when updating functional tests and make it easier to verify that the updates are correct.

Related: #761 (comment)

Alternate proposal: Should we consider migrating to Jest snapshot testing? It does seem like we have accidentally rebuilt this functionality with our test sites 😅

Refer to #771 (comment) for more details