This migrates one bucket of files using some amount of Flow typing to mark them
as TypeScript instead. The remaining type errors are fixed in subsequent
commits.
We use `export default` begrudgingly here. Ideally we'd use just `export`, though this entire SDK expects things to be exported as a default. Instead of breaking everything, we'll sacrifice our export pattern for a smaller diff - a later commit can always do the default export -> regular export conversion.
* Show a spinner while we wait for widgets to be deleted
* Hide widgets while they're pending deletion
* Don't put another jitsi widget into the room if there's already
one pending
