[ty] Request configuration from client (#18984)

## Summary

This PR makes the necessary changes to the server that it can request
configurations from the client using the `configuration` request.
This PR doesn't make use of the request yet. It only sets up the
foundation (mainly the coordination between client and server)
so that future PRs could pull specific settings. 

I plan to use this for pulling the Python environment from the Python
extension.

Deno does something very similar to this.

## Test Plan

Tested that diagnostics are still shown.

crates/ty_server/src/server/api/notifications/did_change.rs

@@ -39,7 +39,7 @@ impl SyncNotificationHandler for DidChangeTextDocumentHandler {
 
         match key.path() {
             AnySystemPath::System(path) => {
-                let db = match session.project_db_for_path_mut(path.as_std_path()) {
+                let db = match session.project_db_for_path_mut(path) {
                     Some(db) => db,
                     None => session.default_project_db_mut(),
                 };