The App Check Core unit tests still have a dependency on Firebase Core (specifically, FirebaseCoreExtension). Updated the imports to framework-style <>, instead of "", since they are coming from the dependency rather than looking for a local path (different repo).
Updated the version from 10.13.0 to 0.1.0-alpha.1 to reflect the pre-release status.
For consistency, renamed both instanceName and storageID to serviceName for consistency.
In all cases, the serviceName is an identifier that differentiates multiple GACAppCheck instances such as when there are multiple FIRApps in use, or multiple dependent SDKs (e.g., Firebase and Google Sign-In). This unique identifier ensures their state is not shared in the Keychain or in User Defaults.
