[Update] Firebase for iOS v8.3.0

Previous PRs: #489, #485, #479

Includes

All projects updated 8.3.0
MLKit for Firebase packages deprecated/removed (no longer supported)
- Firebase.MLKit
- Firebase.MLKit.Common
- Firebase.MLKit.ModelInterpreter
- Firebase.MLKit.NaturalLanguage
- Firebase.MLKit.Vision
- Note: probably need a new project/repo for the newer Google ML Kit bindings
Added beta binding for Firebase App Distribution (Firebase.AppDistribution) & App Check (Firebase.AppCheck)
- excluded for now (no sample or testing done)
Minimum iOS version increased to 10.0

AdMob updated to 8.7.0
Google Cast updated to 4.6.1
Google Maps updated to 5.1.0
Google Places updated to 5.0.0
Google Tag Manager updated to 7.3.1
Deprecated/removed packages (due to outdated Firebase dependencies),
- Google.AppIndexing
- Google.Core
- Google.InstanceID
- Firebase.InstanceID
Minimum iOS version increased to 10.0 (due to Firebase dependencies)

Removed the Wrap methods/properties that where marked as Obsolete (seems like a major version bump is the time to do it 😅).

Added a new build property that can be used to link Firebase with/without Ad ID support.

<PropertyGroup>
  <FirebaseWithoutAdIdSupport>True</FirebaseWithoutAdIdSupport>
</PropertyGroup>

There were quite a few binding changes, so would definitely appreciate someone to look them over. All the samples do run & link as far as I can tell.

UMP has been separated out from AdMob (Google.UserMessagingPlatform).

Any issues let me know!