Exclude Microsoft.Extensions.FileProviders.Embedded from pruning (#63898)

Author: MackinnonBuck

src/Framework/App.Ref/src/Microsoft.AspNetCore.App.Ref.sfxproj

@@ -173,6 +173,13 @@
 
       <!-- Include Microsoft.AspNetCore.App for Package Pruning -->
       <_AspNetCoreAppPackageOverrides Include="$(SharedFrameworkName)|$(ReferencePackSharedFxVersion)" />
+
+      <!--
+        Exclude Microsoft.Extensions.FileProviders.Embedded from pruning because it contains build logic
+        required to generate the embedded files manifest. The package's build targets are not in the SDK,
+        so they must be available from the package itself. See https://github.com/dotnet/aspnetcore/issues/63719
+      -->
+      <_AspNetCoreAppPackageOverrides Remove="Microsoft.Extensions.FileProviders.Embedded|$(ReferencePackSharedFxVersion)" />
     </ItemGroup>
 
     <WriteLinesToFile

src/Framework/test/TargetingPackTests.cs

@@ -144,9 +144,25 @@ public void PackageOverridesContainsCorrectEntries()
             .Split(';', StringSplitOptions.RemoveEmptyEntries)
             .ToHashSet();
 
-        // PackageOverrides will contain all Aspnetcore/Runtime ref pack libs, plus an entry for Microsoft.AspNetCore.App
+        // Some packages are excluded from pruning because they contain build logic that is not in the SDK.
+        // These packages need their build targets to execute even though their runtime assemblies are in the shared framework.
+        string[] packagesExcludedFromPruning = ["Microsoft.Extensions.FileProviders.Embedded"]; // See https://github.com/dotnet/aspnetcore/issues/63719
+
+        foreach (var excludedPackage in packagesExcludedFromPruning)
+        {
+            aspnetcoreDependencies.Remove(excludedPackage);
+        }
+
+        // PackageOverrides will contain all Aspnetcore/Runtime ref pack libs, plus an entry for Microsoft.AspNetCore.App,
+        // minus any packages excluded from pruning
         Assert.Equal(packageOverrideFileLines.Length, runtimeDependencies.Count + aspnetcoreDependencies.Count + 1);
 
+        // Verify that excluded packages are NOT in PackageOverrides
+        foreach (var excludedPackage in packagesExcludedFromPruning)
+        {
+            Assert.DoesNotContain(packageOverrideFileLines, line => line.StartsWith(excludedPackage + "|", StringComparison.Ordinal));
+        }
+
         // PackageOverrides versions should remain at Major.Minor.0 while servicing.
         var netCoreAppPackageVersion = TestData.GetMicrosoftNETCoreAppVersion();
         Assert.True(