This PR updates the user menu in the title bar to base the "signed in"
state on the user in the `CloudUserStore` rather than the `UserStore`.
This makes it possible to be signed-in—at least, as far as the user menu
is concerned—even when disconnected from Collab.
Release Notes:
- N/A
This PR adds two new crates for interacting with Cloud:
- `cloud_api_client` - The client that will be used to talk to Cloud.
- `cloud_api_types` - The types for the Cloud API that are shared
between Zed and Cloud.
Release Notes:
- N/A