Fix a compatibility issue with AnnotationDescriptor

The `getSourceForArgument` method should be in the interface,
but adding it is a breaking change for Java usages,
since the module is not built with -Xjvm-default (KT-54749).

Move the method to an extension. This doesn't change the behavior,
since it was only ever called on LazyAnnotationDescriptor.

core/descriptors/src/org/jetbrains/kotlin/descriptors/annotations/AnnotationDescriptor.kt

@@ -37,7 +37,6 @@ interface AnnotationDescriptor : AnnotationMarker {
 
     val source: SourceElement
 
-    fun getSourceForArgument(name: Name): SourceElement = SourceElement.NO_SOURCE
 }
 
 val AnnotationDescriptor.abbreviationFqName: FqName?

core/descriptors/src/org/jetbrains/kotlin/descriptors/annotations/AnnotationDescriptorImpl.java

@@ -67,12 +67,6 @@ public class AnnotationDescriptorImpl implements AnnotationDescriptor {
         return source;
     }
 
-    @NotNull
-    @Override
-    public SourceElement getSourceForArgument(@NotNull Name name) {
-        return SourceElement.NO_SOURCE;
-    }
-
     @Override
     public String toString() {
         return DescriptorRenderer.FQ_NAMES_IN_TYPES.renderAnnotation(this, null);