to support new Reflection refactoring (#10745)
* uap10.1: moving some APIs from system.io and system.reflection.primitives to corelib
* Revert "uap10.1: moving some APIs from system.io and system.reflection.primitives to corelib"
This reverts commit 0f285f009f4be35a2875bdd535032b14304469b4.
* Moving some types/APIs from S.IO and S.Reflection.Primitives to S.P.CoreLib, to support new Reflection refactoring
The latest build tools contains framework lists for two new Xamarin fxs:
Xamarin.TVOS
Xamarin.WatchOS
This adds placeholders for those frameworks so that they can support
the packages with inbox facades.