* Automatically include *.ttf, *.ttc and *.otf in .NET projects as BundleResource
items (if these files are found within the Resources/ subdirectory).
* Add support for a 'RegisterFont' metadata on BundleResource items, where if set
to 'true', we'll register the font file in the Info.plist as required by the target
platform.
* Add tests.
Fixes https://github.com/xamarin/xamarin-macios/issues/12536.