[WIP] `stale-balance` command: force-sync EigenPods with slashed validators

[jbrower95]

stale-balance

• If an EigenPod has been slashed, you can use stale-balance to start a checkpoint against the EigenPod. We suggest avoiding doing this if the deviated amount is small (<5%), but it is a legal operation within the protocol at any time as a way to sync the beacon state with the execution state, when we know that a beacon slashing has occurred.

• To use;

./cli stale-balance --podAddress $EIGENPOD_ADDRESS --execNode $NODE_ETH --beaconNode $NODE_BEACON --sender $EIGENPOD_PK --slashedValidatorIndex $SLASHED_VALIDATOR_INDEX

This will prompt to complete any in-flight checkpoints, and then call verifyStaleBalances.

[jbrower95]

going to rebase / reopen this.