Fix the duplicate .xbf error after a TerminalControl build (#8754)

Whenever you'd make a change to anything in the Terminal Control
project, then tried deploying the package, you'd get errors like
"Package contains two files with the same name and different content,
files are `Thing.xbf` and
`.../bin/x64/debug/TSM/TerminalControl/Thing.xbf`". It seems like
`GetPackagingOutputs` was double counting these xbfs as being both from
TerminalControl and also TSM&TSE. So if you'd change TerminalControl,
it'd change the xbf files, but not the ones in TSM/TSE, and then
eventually the wapproj would fail to put it all together.

This combination of flags seems to
* make mdmerge work
* make the packaging project work
* make a partial rebuild of TerminalControl followed by a deploy work

I'm hoping that this PR build will confirm that this works in CI as well.

## PR Checklist
* [x] Fixes this minor annoyance I've been having for the past 2 months
* [x] I work here

## Validation Steps Performed
Validated locally on VS 16.8.3. Sure to break by 16.9 🙃.

src/cascadia/TerminalSettingsEditor/Microsoft.Terminal.Settings.Editor.vcxproj

@@ -215,13 +215,34 @@
     <ProjectReference Include="$(OpenConsoleDir)src\cascadia\TerminalConnection\TerminalConnection.vcxproj">
       <Private>false</Private>
     </ProjectReference>
+
     <ProjectReference Include="$(OpenConsoleDir)src\cascadia\TerminalControl\TerminalControl.vcxproj">
-      <Private>false</Private>
+      <!-- Private:false and ReferenceOutputAssembly:false, in combination with
+      the manual reference to TerminalControl.winmd below make sure that this
+      project will compile correct, and that we won't roll up the TermControl
+      xbf's into the packaging project twice. -->
+      <Private>true</Private>
+      <ReferenceOutputAssembly>false</ReferenceOutputAssembly>
     </ProjectReference>
+
     <ProjectReference Include="$(OpenConsoleDir)src\cascadia\TerminalSettingsModel\dll\Microsoft.Terminal.Settings.Model.vcxproj">
       <Private>false</Private>
     </ProjectReference>
   </ItemGroup>
+
+  <ItemGroup>
+    <!-- Manually add a reference to TerminalControl here. We need this so
+    MDMERGE will know where the TermControl types are defined. However, we need
+    to do it exactly like this so the packaging project won't roll up
+    TermControl's .xbf's from both the TermControl project and this one. -->
+    <Reference Include="Microsoft.Terminal.TerminalControl">
+      <HintPath>$(OpenConsoleCommonOutDir)TerminalControl\Microsoft.Terminal.TerminalControl.winmd</HintPath>
+      <IsWinMDFile>true</IsWinMDFile>
+      <Private>false</Private>
+      <CopyLocalSatelliteAssemblies>false</CopyLocalSatelliteAssemblies>
+    </Reference>
+  </ItemGroup>
+
   <Import Project="$(OpenConsoleDir)src\cppwinrt.build.post.props" />
   <Import Project="..\..\..\packages\Microsoft.UI.Xaml.2.5.0-prerelease.201202003\build\native\Microsoft.UI.Xaml.targets" Condition="Exists('..\..\..\packages\Microsoft.UI.Xaml.2.5.0-prerelease.201202003\build\native\Microsoft.UI.Xaml.targets')" />
   <Target Name="EnsureNuGetPackageBuildImports" BeforeTargets="PrepareForBuild">
@@ -231,4 +252,4 @@
     <Error Condition="!Exists('$(OpenConsoleDir)\packages\Microsoft.UI.Xaml.2.5.0-prerelease.201202003\build\native\Microsoft.UI.Xaml.targets')" Text="$([System.String]::Format('$(ErrorText)', '$(OpenConsoleDir)\packages\Microsoft.UI.Xaml.2.5.0-prerelease.201202003\build\native\Microsoft.UI.Xaml.targets'))" />
   </Target>
   <Import Project="$(SolutionDir)build\rules\CollectWildcardResources.targets" />
-</Project>
+</Project>

src/cascadia/TerminalSettingsModel/dll/Microsoft.Terminal.Settings.Model.vcxproj

@@ -59,18 +59,37 @@
     <ProjectReference Include="$(OpenConsoleDir)src\cascadia\TerminalConnection\TerminalConnection.vcxproj">
       <Private>false</Private>
     </ProjectReference>
+
     <ProjectReference Include="$(OpenConsoleDir)src\cascadia\TerminalControl\TerminalControl.vcxproj">
-      <Private>false</Private>
+      <!-- Private:false and ReferenceOutputAssembly:false, in combination with
+      the manual reference to TerminalControl.winmd below make sure that this
+      project will compile correct, and that we won't roll up the TermControl
+      xbf's into the packaging project twice. -->
+      <Private>true</Private>
+      <ReferenceOutputAssembly>false</ReferenceOutputAssembly>
     </ProjectReference>
+
     <!-- Reference Microsoft.Terminal.Settings.ModelLib here, so we can use it's winmd as
     our winmd. This didn't work correctly in VS2017, you'd need to
     manually reference the lib -->
     <ProjectReference Include="$(OpenConsoleDir)src\cascadia\TerminalSettingsModel\Microsoft.Terminal.Settings.ModelLib.vcxproj">
       <Private>true</Private>
-      <CopyLocalSatelliteAssemblies>true</CopyLocalSatelliteAssemblies>
     </ProjectReference>
   </ItemGroup>
 
+  <ItemGroup>
+    <!-- Manually add a reference to TerminalControl here. We need this so
+    MDMERGE will know where the TermControl types are defined. However, we need
+    to do it exactly like this so the packaging project won't roll up
+    TermControl's .xbf's from both the TermControl project and this one. -->
+    <Reference Include="Microsoft.Terminal.TerminalControl">
+      <HintPath>$(OpenConsoleCommonOutDir)TerminalControl\Microsoft.Terminal.TerminalControl.winmd</HintPath>
+      <IsWinMDFile>true</IsWinMDFile>
+      <Private>false</Private>
+      <CopyLocalSatelliteAssemblies>false</CopyLocalSatelliteAssemblies>
+    </Reference>
+  </ItemGroup>
+
   <Import Project="$(OpenConsoleDir)packages\Microsoft.UI.Xaml.2.5.0-prerelease.201202003\build\native\Microsoft.UI.Xaml.targets" Condition="Exists('$(OpenConsoleDir)packages\Microsoft.UI.Xaml.2.5.0-prerelease.201202003\build\native\Microsoft.UI.Xaml.targets')" />
   <Target Name="EnsureNuGetPackageBuildImports" BeforeTargets="PrepareForBuild">
     <PropertyGroup>