This diff is a partial revert of D10453.
As part of the conflicting proof management, we need to be able to accept or reject a proof depending on the avalanche vote, i.e. bring back a proof from orphans and turn it into a peer, or remove a peer and make it an orphan.
In this case the cooldown time should not happen, but proof validation is still needed. The current proof pool design causes D10453 to be in the way of this feature, as it makes it impossible to call createPeer without duplicating the proof verification, so this diff reverts that.
The orphan proof removal is also added back; strictly speaking it's not needed, but it makes the code easier to reason about. Next step is to pass the cooldown value to createPeer.
There is no change in behavior.
Ref T1854.
Depends on D10525.