Combine "startup" & "server.initialized" telemetry events

[rgrunber]

If a user has opted-in, we send 2 events on startup of the extension. One purely from the client side, and one from the server side. It would be good to combine these into one. Maybe the "startup" event should wait for the "server.initialized" event, or something to that effect.

Main problem is that, if "server.initialized" fails, there's no server to send the event for failure, so "startup" shouldn't wait. Either some timeout, or a way for the client to check if the server failed.

[rgrunber]

Maybe @JessicaJHee is interested in having a look at this.