Core SDK 1.6.0

Updates

1. Feature

   Added: `UnityServices.ExternalUserId` which can be used to pass a user identifier from a third party provider to Unity Gaming Services.

2. Feature

   Added: All `IInitializablePackage` initialization time is now measured by Services Core.

3. Change

   Changed: `CoreRegistryInitializer` now throws a `ServicesInitializationException` instead of an explicit `NullReferenceException` when the dependency tree is null.

4. Improvement

   Changed: ActionScheduler updated to be thread safe.

5. Feature

   Changed: Services configuration file isn't temporarily added to the StreamingAssets folder during builds on Unity 2021.3 and up.

6. Change

   Changed: Services initialization without a linked project ID now fail (throw `UnityProjectNotLinkedException` ).

7. Fix

   Fixed: Persisting telemetry no longer logs errors, unless `ENABLE_UNITY_SERVICES_CORE_TELEMETRY_LOGGING` is enabled as scripting define. Diagnostics are sent when persisting telemetry produces an error.

8. Fix

   Fixed: Core no longer fails initialization when it fails to find a stripped service package.

9. Fix

   Fixed: Services Core failing to find all `IInitializablePackage` if an unity package implements it multiple times.

10. Fix

    Fixed: A case where null configuration values were causing serialization issues.

11. Fix

    Fixed: Issue with stripping when authentication APIs are not used.