[build] Output templates pack to lowercase path (#7167)

Workload template packs installed into the `template-packs` folder
should have a lowercased package ID.  This was not accounted for when
updating local build behavior in commit c21e78c.  Fix the path that we
"install" our template pack into for local builds so that the templates
can be resolved on Linux.

Author: pjcollins

build-tools/create-packs/Directory.Build.targets

@@ -216,7 +216,7 @@
     <_RuntimeListOutputs Include="@(AndroidSupportedTargetJitAbi->'$(BuildOutputDirectory)lib\packs\Microsoft.Android.Runtime.$(AndroidLatestStableApiLevel).%(AndroidRID)\$(AndroidPackVersion)\data\RuntimeList.xml')" AndroidRID="%(AndroidRID)" />
     <_RuntimeListOutputs Include="@(AndroidSupportedTargetJitAbi->'$(BuildOutputDirectory)lib\packs\Microsoft.Android.Runtime.$(AndroidLatestUnstableApiLevel).%(AndroidRID)\$(AndroidPackVersion)\data\RuntimeList.xml')" AndroidRID="%(AndroidRID)" />
     <_TemplatesInputs Include="$(XamarinAndroidSourcePath)src\Microsoft.Android.Templates\**" />
-    <_TemplatesOutputs Include="$(BuildOutputDirectory)lib\template-packs\Microsoft.Android.Templates.$(AndroidPackVersion).nupkg" />
+    <_TemplatesOutputs Include="$(BuildOutputDirectory)lib\template-packs\microsoft.android.templates.$(AndroidPackVersion).nupkg" />
   </ItemGroup>
 
   <Target Name="CreateLocalRuntimeLists"
@@ -247,6 +247,7 @@
       <_PackProps Include="-p:IncludeSymbols=False" />
       <_PackProps Include="-p:OutputPath=$(DotNetPreviewPath)template-packs" />
       <_PackProps Include="-p:TemplatePackVersion=$(AndroidPackVersion)" />
+      <_PackProps Include="-p:PackageId=microsoft.android.templates" />
     </ItemGroup>
     <Exec Command="&quot;$(DotNetPreviewTool)&quot; pack @(_PackProps, ' ') &quot;$(XamarinAndroidSourcePath)src\Microsoft.Android.Templates\Microsoft.Android.Templates.csproj&quot;" />
   </Target>