Enhancement: Add Selected Corpus Indicator in <DocumentAnnotator/>

[JSv4]

This component has been radically redesigned and refactored so it can be used accross the application where we had three (kludy) versions of the same thing before. One slight complication now though, is when you navigate between views, you may want to leave certain global filters on - like filtering to data in an opened_corpus - BUT we need to make it clear to user this filter is still being applied.

Here's an example flow - user is in corpus view and has a corpus opened. They then click the "Document" tab to look at all documents. They click a doc to open. The will load permissions and data from the opened corpus. That means the user might be able to actually annotate the corpus or provide feedback to a corpus they probably don't recall offhand... and this will likely not be expected. Having an indicator somewhere will make this much easier and also let the user unselect the corpus. Thanks to new annotation loading and data handling, this will also not break anything.

[JSv4]

Resolved via #266