Google Drive: Add a feature flag (#37358)

In order to develop the site keyring connection for Google Drive, we
need to be able to enable the option on the server side, without it
appearing in the list of available connections.

So far we have done this by restricting the connection to Automatticians
on the server side, but this has caused other problems. This change
creates and configures a feature flag, so that the connection is only
available in the development environment.

client/state/sharing/services/selectors.js

@@ -119,6 +119,14 @@ export function getEligibleKeyringServices( state, siteId, type ) {
 			return false;
 		}
 
+		if (
+			'google_drive' === service.ID &&
+			( ! config.isEnabled( 'google-drive' ) ||
+				! canCurrentUser( state, siteId, 'manage_options' ) )
+		) {
+			return false;
+		}
+
 		return true;
 	} );
 }

config/development.json

@@ -58,6 +58,7 @@
 		"external-media/free-photo-library": true,
 		"gdpr-banner": false,
 		"google-my-business": true,
+		"google-drive": true,
 		"gutenboarding": true,
 		"help": true,
 		"help/courses": true,