WIP: API for uploading and getting info from LSIF db

What does this MR do?

Provides prototype of the API for uploading LSIF dump and getting ranges/hovers/definitions information from it by the following endpoints:

• http://localhost:3000/api/v4/projects/20/commits//lsif/upload
• http://localhost:3000/api/v4/projects/20/commits/1/lsif/info?path=cmd/check/main.go

Related: #196514 (closed)