validatorCandidates

Table storing preactive/candidate validators, mapping their addresses to their Validator structs. When an address calls request_add_validator_candidate, they get added to this table and become a preactive validator. When the candidate has met the min stake requirement, they can call request_add_validator to officially add them to the active validator set active_validators next epoch.

key: address (sui address of the validator), value: 0x3::validator_wrapper::ValidatorWrapper