[WASM] Use `manifest.json` for `PackageId.Version`

What would you like to be added:

If the app has a manifest.json, we should use its version property (if it is defined) for PackageId.Version as opposed to Assembly version.

Why is this needed:

To verify running application version

For which Platform:

• [ x] iOS
• [ x] Android
• [ x] WebAssembly
• [ x] WebAssembly renderers for Xamarin.Forms
• [ x] macOS
• [ x] Skia
  • [x ] WPF
  • [ x] GTK (Linux)
  • [ x] Tizen
• [ x] Windows
• Build tasks
• Solution Templates

Anything else we need to know?

It seems like an odd thing to not be implemented.