Adding ExtensionManager dll to dlls folder

Author: dgosbell

DLLs/SQL2019/Reference/Microsoft.VisualStudio.ExtensionManager.dll

@@ -928,7 +928,7 @@
     </Reference>
     <Reference Include="Microsoft.VisualStudio.ExtensionManager, Version=14.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a, processorArchitecture=MSIL">
       <SpecificVersion>False</SpecificVersion>
-      <HintPath>..\..\..\..\..\Program Files (x86)\Microsoft Visual Studio\2019\Enterprise\Common7\IDE\PrivateAssemblies\Microsoft.VisualStudio.ExtensionManager.dll</HintPath>
+      <HintPath>DLLs\SQL2019\Reference\Microsoft.VisualStudio.ExtensionManager.dll</HintPath>
     </Reference>
     <Reference Include="Microsoft.VisualStudio.ImageCatalog, Version=15.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a, processorArchitecture=MSIL">
       <HintPath>packages\Microsoft.VisualStudio.ImageCatalog.15.9.28307\lib\net45\Microsoft.VisualStudio.ImageCatalog.dll</HintPath>