We can’t remove all app groups from an App ID once one has been assigned, but we _can_ disable app groups completely for effectively the same result.
This fixes some apps having permanant access to AltStore’s own app group after being (de-)activated.
Apple’s servers return an error when registering a bundle ID with different capitalization than an existing one, so we now perform case-insensitive comparisons when determining if we need to register an App ID.
Assuming the certificate used to originally sign an app is still valid, we can refresh an app simply by installing new provisioning profiles. However, if the signing certificate is no longer valid, we fall back to the old method of resigning + reinstalling.
