refactor: import common targets, centrally

Author: earloc

Diff for: Directory.Build.targets

@@ -21,7 +21,7 @@
     <NoWarn>$(NoWarn);Nullable</NoWarn>
   </PropertyGroup>
 
-  <Import Project="eng\targets\Packaging.targets" />
+  <Import Project="eng\targets\Common.targets" />
 
   <!-- Workaround https://github.com/dotnet/cli/issues/10528 -->
   <PropertyGroup>

Diff for: eng/targets/Common.targets

@@ -0,0 +1,4 @@
+<?xml version="1.0" encoding="utf-8"?>
+<Project>
+  <Import Project="Packaging.targets" />
+</Project>