Write full synthetic method signature for annotated property

This will be needed to support annotated extension properties, since they have
the same name but different signatures
Fix synthetic method generation for extension properties

If several annotated extension properties with the same name were declared in
one class, JVM issued a ClassFormatError, since we generated a synthetic method
for each of them with the same name and signature. Make the signature of this
synthetic method depend on a receiver parameter, if a property has one
Don't generate synthetic method body for annotated property in trait