Add CMake setting for iOS product bundle identifiers

[docEdub]

The iOS product bundle identifiers need to be changed when building locally for development purposes but are hard-coded as "com.BabylonNative.Playground.iOS" and "com.BabylonNative.ValidationTests.iOS".

This change adds CMake settings for the iOS product bundle identifiers so they can be changed without modifying the CMake files directly.

[ghost]

All CLA requirements met.

[ryantrem]

The iOS product bundle identifiers need to be changed when building locally for development purposes

Why? What problem is this solving? Not too familiar with product bundle ids.

[docEdub]

The iOS product bundle identifiers need to be changed when building locally for development purposes

Why? What problem is this solving? Not too familiar with product bundle ids.

On my machine I get a bundle id error when building for iOS devices:

error: Failed to register bundle identifier: The app identifier "com.BabylonNative.Playground.iOS" cannot be registered to your development team because it is not available. Change your bundle identifier to a unique string to try again.

Changing the id gets the build working.

[bghgary]

That sounds like something else is wrong. I don't think we need this change.