Allow REStake for validators commission

[geldmon]

Would like to see autostake for validators via self-delegate address. This should work as follows:

1. if the address is the validator self-delegate address
2. and if granted the WithdrawDelegatorReward permission

This would allow validators to autowithdraw and autostake if the Delegate permission is also given.

[tombeynon]

Just to clarify - do you mean auto-compounding the validator's commission? Because auto-compound rewards would work now if the validator grants permission to the restake address as normal. But I agree commission would be a nice addition, and easy enough to implement. Just need to handle WithdrawalValidatorCommission

[geldmon]

Yes, exactly