Allow inbound number filtering on SIP Dispatch Rules. It works similar to Trunks, where rules without a number filter are grouped together and take less priority than number-specific rules.
While at it, simplify the rule evaluation.
Previously it was doing some hand-crafted checks for evaluation path, that matched the validation path. Same double logic existed for priorities as well.
Now the validation is always called from evaluation, thus sharing the logic. And rule selection is simplified by just picking the first one after priority filtering.
