Use @@ to whitelist in ABP style adlists

Feature Requests Partially-implemented
63

The first PRs are online for discussion:

https://github.com/pi-hole/pi-hole/pull/5330

https://github.com/pi-hole/FTL/pull/1579

The web PR is still to follow, but I ran out of time yesterday evening

edit Added web PR

https://github.com/pi-hole/AdminLTE/pull/2618