Add InternalsVisibleTo and remove duplicate shared source files to enable UserManagerMetrics registration

Co-authored-by: captainsafia <[email protected]>

Author: Copilot

src/Identity/Core/src/Microsoft.AspNetCore.Identity.csproj

@@ -14,8 +14,6 @@
 
   <ItemGroup>
     <Compile Include="$(SharedSourceRoot)DefaultMessageEmailSender.cs" LinkBase="Shared" />
-    <Compile Include="$(SharedSourceRoot)Metrics\MetricsConstants.cs" LinkBase="Shared" />
-    <Compile Include="$(SharedSourceRoot)ValueStopwatch\ValueStopwatch.cs" LinkBase="Shared" />
   </ItemGroup>
 
   <ItemGroup>

src/Identity/Extensions.Core/src/Microsoft.Extensions.Identity.Core.csproj

@@ -29,6 +29,7 @@
   </ItemGroup>
 
   <ItemGroup>
+    <InternalsVisibleTo Include="Microsoft.AspNetCore.Identity" />
     <InternalsVisibleTo Include="Microsoft.AspNetCore.Identity.Specification.Tests" />
     <InternalsVisibleTo Include="Microsoft.AspNetCore.Identity.Test" />
     <InternalsVisibleTo Include="Microsoft.AspNetCore.Identity.EntityFrameworkCore.Test" />