Make QuarkusArtifactHandler back to being @singleton

This was changed in:
#52016
together with a bunch of other components.

But this particular component needs to exist even if not in a session as
demonstrated in kordamp/pomchecker#38 .

Author: gsmet

devtools/maven/src/main/java/io/quarkus/maven/components/QuarkusArtifactHandler.java

@@ -1,11 +1,11 @@
 package io.quarkus.maven.components;
 
 import javax.inject.Named;
+import javax.inject.Singleton;
 
-import org.apache.maven.SessionScoped;
 import org.apache.maven.artifact.handler.ArtifactHandler;
 
-@SessionScoped
+@Singleton
 @Named("quarkus")
 public class QuarkusArtifactHandler implements ArtifactHandler {