Explore using TypeSense as a database backend, replacing MongoDB

[stefandesu]

TypeSense is not a database per se, but since a lot of what we're using MongoDB for in this project is filtering and searching, it might make sense to completely replace MongoDB with TypeSense. I could imagine seeing huge performance improvements with this, although the migration is not trivial, of course.

See also: #188

Doing this might make the following issues much easier or even unnecessary:

• Improve performance of mapping search by creator #170
• Endpoints that return many concepts are slow #151
• Issues with long-running database processes #148
• Combine fulltext search and filtering? #144
• Use $lookup/$graphLookup to determine ancestors/narrower/annotations if requested via properties #130
• Filter search on top concepts #128
• Enable stopwords in search/suggest #123
• Search/Typeahead: Fallback to word stem if there are no results #50

Some things could also become more difficult, like #88.

It might also make sense to consider graph databases (maybe even in combination with TypeSense), as some things we're doing, and some things that we would like to do in the future, are graph-based.