Fix permission check for net

[bartlomieju]

Closes #2371

It turns out we were checking for "listen", "dial" and "accept" addresses in net permissions 😅

I removed check in op_accept because we need to first issue op_listen and there is already check there.

[ry]

Thanks! Is it possible to add a test to tools/complex_permissions_test.py that demos this fix? (Presumably, for example, listen wasn't properly obeying --allow-net arguments before.)

[bartlomieju]

Sorry @ry, should have started with tests in the first place, turns out my initial solution was wrong 😉 I guess it's worth mentioning in the docs that --allow-net=addr1,addr2 allows to access addr1 and addr2 before they are resolved

[ry]

LGTM - thanks for this fix!