Preserve dependency scope in plugin artifacts

What changed:
- Added `RepositoryUtils.toArtifact(ArtifactResult)` to convert resolved artifacts and copy dependency metadata from the resolution request.
- Set Maven `Artifact` scope and optional flag from the resolved dependency node instead of converting only the raw Aether artifact.
- Updated `DefaultMavenPluginManager` to use the new conversion path for plugin realm and extension artifact resolution.

Why:
- `PluginDescriptor.getArtifacts()` returned artifacts with `null` scope in Maven 3.10.0-rc-1.
- Restoring scope/optional metadata brings behavior back in line with 3.9.x and avoids regressions in plugins that depend on artifact scope.

fix #12497

Author: slawekjaranowski

maven-core/src/main/java/org/apache/maven/RepositoryUtils.java

@@ -50,6 +50,8 @@
 import org.eclipse.aether.repository.RepositoryPolicy;
 import org.eclipse.aether.repository.WorkspaceReader;
 import org.eclipse.aether.repository.WorkspaceRepository;
+import org.eclipse.aether.resolution.ArtifactRequest;
+import org.eclipse.aether.resolution.ArtifactResult;
 import org.eclipse.aether.util.repository.AuthenticationBuilder;
 
 /**
@@ -156,6 +158,27 @@ public static Artifact toArtifact(org.apache.maven.artifact.Artifact artifact) {
         return result;
     }
 
+    /**
+     * @since 3.10.0
+     */
+    public static org.apache.maven.artifact.Artifact toArtifact(ArtifactResult artifactResult) {
+
+        if (artifactResult == null || artifactResult.getArtifact() == null) {
+            return null;
+        }
+
+        org.apache.maven.artifact.Artifact artifact = toArtifact(artifactResult.getArtifact());
+        Optional.ofNullable(artifactResult.getRequest())
+                .map(ArtifactRequest::getDependencyNode)
+                .map(DependencyNode::getDependency)
+                .ifPresent(d -> {
+                    artifact.setScope(d.getScope());
+                    artifact.setOptional(d.isOptional());
+                } );
+
+        return artifact;
+    }
+
     public static Dependency toDependency(
             org.apache.maven.artifact.Artifact artifact, Collection<org.apache.maven.model.Exclusion> exclusions) {
         if (artifact == null) {

maven-core/src/main/java/org/apache/maven/plugin/internal/DefaultMavenPluginManager.java

@@ -396,7 +396,7 @@ private void createPluginRealm(
 
         pluginArtifacts = result.getArtifactResults().stream()
                 .filter(ArtifactResult::isResolved)
-                .map(r -> RepositoryUtils.toArtifact(r.getArtifact()))
+                .map(RepositoryUtils::toArtifact)
                 .collect(Collectors.toList());
 
         pluginRealm = classRealmManager.createPluginRealm(
@@ -831,7 +831,7 @@ private List<Artifact> resolveExtensionArtifacts(
                 pluginDependenciesResolver.resolvePluginAndFlatten(extensionPlugin, null, null, repositories, session);
         return result.getArtifactResults().stream()
                 .filter(ArtifactResult::isResolved)
-                .map(r -> RepositoryUtils.toArtifact(r.getArtifact()))
+                .map(RepositoryUtils::toArtifact)
                 .collect(Collectors.toList());
     }
 }