Refactor packages and add exception handler.

Renamed various classes to follow the "controlers" package structure for better organization and consistency. Added `ControllerExceptionHandler` to manage validation exceptions globally and improve error logging.

src/test/java/TestForm.java

@@ -1,4 +1,4 @@
-import com.alttd.forms.contact.ContactFormData;
+import com.alttd.forms.controlers.contact.ContactFormData;
 import com.alttd.forms.form.StoreFormQuery;
 import com.alttd.forms.database.DatabaseConnection;
 import com.alttd.forms.form.Form;