Automatically project referenced WinRT components without CsWinRTIncludes

[Scottj1s]

Repro sample here:
https://github.com/Scottj1s/ReunionCsAppWithCppRC/blob/22a8792d54a15c3ace13e131808e63300635a7f0/App3/App3/App3.csproj#L6

CsWinRTWindowsMetadata should default to TargetPlatformMinVersion. And CsWinRTIncludes should default to enabling anything which is not expressly in CsWinRTExcludes (Microsoft, Windows).

[angelazhangmsft]

#657 closes CsWinRTWindowsMetadata issue