Add the right for changing descriptors not overall, but per hitlist

Currently i can give the Right to change descriptors only in general; yes or no. So users with it can use it on all hitlists, or none. Especially in bigger organisations when you give that right to someone who is a key user for A, he is able to use it in B and C, too (where he's only a normal user). And key users in B and C are able to edit in A, too. This can cause misstakes and make it harder to retrace.

So i want to allow Key Users of A to mass edit A but not B, and Key Users of B to edit B, but not A.