[lsp] short circuit code actions if client doesn't support quickfixes
[lsp] short circuit code actions if client doesn't support quickfixes

Summary: all of our code actions are currently quick fixes, so if the client says it doesn't support those, then don't bother parsing and typechecking the file just to do nothing.

Reviewed By: nmote

Differential Revision: D24287387

fbshipit-source-id: 1cd9b724e2a8f3c31ac405be900866c46aa567f0

facebook/flow,facebook/flow,mroch/flow,mroch/flow,facebook/flow,mroch/flow,mroch/flow,mroch/flow,facebook/flow,mroch/flow,facebook/flow,mroch/flow,facebook/flow,facebook/flow