[Activate Project] Show loading spinner while features load

[gino-m]

When activating or joining a project, the loading spinner disappears as soon as the project metadata is loaded, but before the map features are fully loaded. The app lags while the features are being loaded, and in some cases the map will seem incomplete until the features are loaded. Instead of allowing the user to start interacting with the app, the spinner should remain until all features have been loaded.