🎨 Refactor: move route func's to separate handlers

[ff137]

Move all the route handling functions to separate modules in routes/handlers/. Makes it easier to maintain routes/spec.js, and to write tests for each route.

Which reminds me. Todo: write tests for each route!

[howardchung]

This will need a rebase. But my intent was for queries.ts to hold most of the business logic as well as provide testable interfaces. We don't necessarily need to split each set of functions into a separate file, I think