LSIF: Add additional LSIF intelligence endpoints
Created by: efritz
This PR adds additional endpoints that will aid queries from the frontend to support the LSIF GraphQL API resolvers as described in RFC 74.
The new endpoints are:
- GET
/definitions?repository,commit,path,line,character
- GET
/references?repository,commit,path,line,character,limit,cursor
- GET
/hover?repository,commit,path,line,character
These are basically the same responses from the /request
endpoint, but returns a more "exploded" view of the data. Instead of a single URI for locations, it returns the repository, commit, path, and range as a JSON object.