LSIF Backend Scaling
Created by: efritz
This PR splits the lsif-server into two parts:
- the lsif-server that answers LSP queries, and
- the lsif-worker that converts LSIF dump payloads into SQLite databases.
See this doc for discussion and motivation.
- Created second entrypoint, necessitated a new docker images, build script, yarn commands, and a change to ./cmd/server and the dev procfile
- reorganized settings (as they are now shared by two applications)
- removed backend, as it was just a dumb shim for initializing a database instance after the split
For now we assume that the lsif-worker will not be scaled to multiple processes, which requires some additional thought about how to concurrently write to SQLite (or to use an external client-server db).