[reSIProcate] Added new RequestValidationHandler to DUM on trunk

[Francis Joanis <francis.joanis@xxxxxxxxx>]

Hi,

I've added a new handler that enables DUM applications to know when an incoming request is rejected because of a failed validation.

For example, onInvalidMethod(const SipMessage& request) will be called on the registered handler if a request is received with an unsupported SIP method.

The default behavior is to have no such handler. You can register your handler using DialogUsageManager::setRequestValidationHandler.

I've also added a testRequestValidationHandler test (under dum/test) that shows how to use it (note that not all callbacks are tested in there).

Please let me know if you have any comment.

Regards,

Francis