[Assp-test] Difference between MSG-ID missing and MSG-ID invalid

[Jean-Pierre v. M. <jp...@mi...>]

Like with PTR-invalid, make a difference between MSG-ID missing and MSG-ID invalid.

There is also no way of validating a MSG-ID or a "don't score MSG-ID from these IP's"
The code to see if the MSG-ID is now hardcoded, this could be the same as with HELO and PTR.