[Windows] Skip running tasks with no inputs

This is a very minor perf improvements that could help when building remotely from Windows with slow connections (i.e., from Devbox).

It skips running some tasks that not always have inputs to avoid the unnecessary network round tripping.

Author: emaf

dotnet/targets/Xamarin.Shared.Sdk.targets

@@ -856,7 +856,7 @@
 		<!-- Figure out which frameworks are really dynamic libraries, and only publish those -->
 		<FilterStaticFrameworks
 			SessionId="$(BuildSessionId)"
-			Condition="'$(IsMacEnabled)' == 'true'"
+			Condition="'$(IsMacEnabled)' == 'true' And '@(_FrameworkToPublish)' != ''"
 			FrameworkToPublish="@(_FrameworkToPublish)"
 		>
 			<Output TaskParameter="FrameworkToPublish" ItemName="_FilteredFrameworkToPublish" />
@@ -873,7 +873,7 @@
 
 		 -->
 		<GetFullPaths
-			Condition="'$(IsMacEnabled)' == 'true'"
+			Condition="'$(IsMacEnabled)' == 'true' And '@(_FilteredFrameworkToPublish)' != ''"
 			SessionId="$(BuildSessionId)"
 			Items="@(_FilteredFrameworkToPublish)"
 			Metadata="Identity;SourceDirectory"
@@ -2620,6 +2620,7 @@ global using nfloat = global::System.Runtime.InteropServices.NFloat%3B
 
 		-->
 		<GetFileSystemEntries
+			Condition="'@(_BindingPackagesFromReferencedAssembliesDirectoriesExists)' != ''"
 			SessionId="$(BuildSessionIdIfConnected)"
 			DirectoryPath="@(_BindingPackagesFromReferencedAssembliesDirectoriesExists)"
 			Pattern="*"

msbuild/Xamarin.iOS.Tasks.Windows/Xamarin.iOS.Common.After.targets

@@ -306,7 +306,7 @@ Copyright (C) 2011-2013 Xamarin. All rights reserved.
 		destination doesn't exist, the source is newer than the destination, or if the source and
 		destination differ by file size.
 		-->
-		<Copy Condition="'$(IsMacEnabled)' == 'true'"
+		<Copy Condition="'$(IsMacEnabled)' == 'true' And '@(_ResolvedFileToPublishAlways)' != ''"
 			SessionId="$(BuildSessionId)"
 			SourceFiles = "@(_ResolvedFileToPublishAlways)"
 			DestinationFiles="@(_ResolvedFileToPublishAlways->'$(PublishDir)%(RelativePath)')"