Cohost LSP client initialization follow up

[davidwengier]

In #11129 we started sending client capabilities to OOP in cohosting, which is great, but we only do it once. To be correct we need to do a couple more steps:

1. When the LSP server is shut down, we should "unitialize" OOP capabilities. ie, CanGetClientCapabilties should return false.
   • This would also be a good time to clear caches (eg, completion, inlay hints) and other things
2. When the LSP server restarts again, we should ensure we re-initialize OOP.

Note that by "uninitialize" I don't mean shut down, and by "re-initialize" I mean only the LSP initialization options, not the regular ones.

Also, in case it's not known or clear, in VS the LSP server is shut down when a solution is closed, and restarted when a new one is opened, and a C# file opened in the editor.