codeintel: Call query methods from from lsifserver client
Created by: efritz
This is step two into collapsing the precise-code-intel-api-server into the frontend. We expose the necessary logic to call the query endpoints directly from the lsifserver client.
https://github.com/sourcegraph/sourcegraph/pull/10871 does the same thing for the upload endpoint.
These PRs are meant to create minimal diffs. A secondary clean-up effort to remove dead code and reduce call graph layers will be done after these lands.
Note to reviewers: The new files in the lsifserver/client package are not new - they're copy/pasted from cmd/precise-code-intel-api-server/internal/server. They shouldn't need any additional review.