[dotnet] Add some project capabilities. (xamarin#9013)

* [.NET 5] Start adding some project capabilities (#3)

Aligned with XA too, see dotnet/android#4383.

We'll start using Apple instead of iOS for these things at the IDE level since many
behaviors don't actually depend on iOS but also apply to tvOS, watchOS, and so on.

These capabilities go before other imports just in case additional packages/targets
from the SDK need to access them too.

* Remove the LaunchProfiles capability for the CPS integration (xamarin#8472)

Implements https://work.azdo.io/1112733 as a workaround for the conflicts between
the built-in launchsettings.json-based .NET Core debugger and our Mono debugger.

Co-authored-by: Daniel Cazzulino <daniel@cazzulino.com>

dotnet/targets/Xamarin.Shared.Sdk.targets

@@ -1,6 +1,16 @@
 <?xml version="1.0" encoding="utf-8"?>
 <Project DefaultTargets="Build" xmlns="http://schemas.microsoft.com/developer/msbuild/2003">
 
+	<!-- Automatically supply project capabilities for IDE use -->
+	<ItemGroup>
+		<ProjectCapability Include="Apple" />
+		<ProjectCapability Include="Mobile" />
+
+		<!-- See https://work.azdo.io/1112733 -->
+		<!-- Conflicts with our targets generator in VS+CPS -->
+		<ProjectCapability Remove="LaunchProfiles" />
+	</ItemGroup>
+
 	<PropertyGroup>
 		<_XamarinTaskAssembly Condition="'$(_PlatformName)' != 'macOS'">$(_XamarinSdkRootDirectory)\tools\msbuild\iOS\Xamarin.iOS.Tasks.dll</_XamarinTaskAssembly>
 		<_XamarinTaskAssembly Condition="'$(_PlatformName)' == 'macOS'">$(_XamarinSdkRootDirectory)\tools\msbuild\macOS\Xamarin.Mac.Tasks.dll</_XamarinTaskAssembly>