Use builder logic (now used for compile on save) to retrieve diagnostics for tsserver

[mhegazy]

Now that we have the builder logic that optimizes what files to read. we should use this for getDiagnostics.

[PFight]

Can we hope to see this sometime?
Comple-on-save is awesome feature for large-scale projects, it is very sad, that no one editor can support it well (and VSCode not support at all) without this.

[TomasHubelbauer]

Would be really cool to get at least a rough estimate (this year?) as this is a blocker for microsoft/vscode#13953 which is very painful.

[andrecasal]

Would love a status update on the progress for this feature from the TS team. Like @TomasHubelbauer said, this is a missing key feature in VS Code (microsoft/vscode#13953) and a deal breaker for large projects.

[olafur-palsson]

Any status updates so far? It's been a couple of years now. This is now a much needed feature for the typescript.tsserver.experimental.enableProjectDiagnostics feature in vscode which is currently using the geterrForProject route.