Restore reward eligibility in the Random Beacon sortition pool

[pdyraga]

In case the operator was marked as ineligible for rewards, the client needs to monitor the ineligibility status and restore the eligibility as soon as possible.

References:

https://github.com/keep-network/sortition-pools/blob/b3fcb43e09d9fc2304fa2f65635aec406a6cfe79/contracts/SortitionPool.sol#L140-L152

https://github.com/keep-network/sortition-pools/blob/b3fcb43e09d9fc2304fa2f65635aec406a6cfe79/contracts/Rewards.sol#L74-L99