Backport Retriever prototype improvements

[tokebe]

The Retriever prototype in BioPack has a few experimental improvements over BTE which should be brought back to BTE.

The general list of changes we should backport are as follows:

• Refactor/stricter typing of interthread communication
• New single subquery queue
• New caching system using hashed subqueries instead of QEdges

These changes are spread across much of the codebase, but should be relatively trackable via commits thanks to Retriever being a single repo. Primary changes are in the thread handler, call-apis package, and new utils caching file, respectively. Along with this, a new graph package was split off, as well as numerous changes in the types package, most of which are likely necessary for the changes to the primary packages to work.

For this backporting, we don't want to worry about any name changes. Additionally, feature removals (such as removing inferred mode) aren't desired -- those were purely for Retriever's use case. It's probably easiest to manage by going chronologically up the new commits, starting from where the packages were added locally, and working changes back into the appropriate BTE packages while ignoring any change that appears to be just a renaming or feature removal.

[rjawesome]

PRs are functionally done but I am still working on updating the tests