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

[ghost]

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.

[MartinZikmund]

@GRS-Leedo this is surely implementable, the only question is where should the version be coming from. For Android, iOS, UWP, the package version is part of the application manifest. For the web, would you consider the version in manifest.json to be the right one to show up there?

[ghost]

Yes, I believe that would be the one to use.

[MartinZikmund]

This is now implemented by #12596 on all platforms, but on WASM it uses assembly version