Add more tests for dev tunnel hosting integration

- Verify that options are validated, e.g. labels
- Verify interaction between tunnel resources and `IDevTunnelClient` for various scenarios, e.g. ensuring tunnel is created/updated with current options, access control, etc.
- Verify that tunnel port status is updated in reaction to changes to parent tunnel resource, start/stop, restart, etc.
- Verify that attempting to tunnel to resources with non-HTTP or non-localhost endpoints throws appropriate exceptions
- Verify that auth state scenarios behave as expected, e.g.:
- When not authenticated tunnel resource should fail to start and notification should be shown
- Only one authn notification should be shown at a time no matter how many tunnel resources there are
- Authn notification should be reshown after dismissed when tunnel resource is next started
- Authn notification should not be shown when user is authenticated
- Authn notification should reappear if authentication attempt fails
- Verify devtunnel CLI detection shows notification when CLI is not detected (again, only one at a time no matter how many tunnel resources there are)
- Verify devtunnel CLI detection honors configuration setting to set custom path to devtunnel CLI