External references are not always found if project did not finish loading yet

[felixfbecker]

There is currently no way for the backend to know when tsserver finished loading a project. Therefor references results often come back empty.

A solution to this would be to subclass the TypeScript langserver and interact with tsserver directly to get access to the tsserver events and requests for loading projects:

https://sourcegraph.com/github.com/Microsoft/TypeScript@b8def16e92f609327971f07232757fa6c7d29a56/-/blob/src/server/protocol.ts#L1430-1436

https://sourcegraph.com/github.com/Microsoft/TypeScript@b8def16e92f609327971f07232757fa6c7d29a56/-/blob/src/server/protocol.ts#L2459-2463