[fixes #2838] Handle anonymous classes properly

Generated qualified names (e.g. Outer.Inner) now stop at anonymous
classes instead of adding an empty part. All handlers that add static
fields/methods/types now add error messages instead of generating
invalid code.

test/transform/resource/before/ToStringInAnonymousClass.java

@@ -0,0 +1,10 @@
+import lombok.ToString;
+
+public class ToStringInAnonymousClass {
+	Object annonymous = new Object() {
+		@ToString
+		class Inner {
+			private String string;
+		}
+	};
+}