Fix for validation of @Macro

Ann error was reported for a macro bound to an overloaded method. In
that case all alternatives have been validated, which is incorrect.
The validation will happen only for the single method with matching
arity. If no such method is found, a quick fix to create a new method
 is shown. If one method with broken signature is found, a fix to
 change its signature is shown as well since we believe this is the
 common case.