Add precise-code-intel system integration tests (rough v0)
Created by: efritz
Add ./internal/cmd/precise-code-intel-test
as a rough integration test for precise code intel services. I wrote this now so that we can ensure that we have good coverage when we switch between TS and Go backends.
This will eventually become our precise code intel integration tests (tests for each language/indexer) for as well as our LSIF API load tester.
The interface is not super great right now, but it gets the job done and one of code intel's Q2 goals is to polish this thing up.