Ledger: StorageDescriptor<[Key: SS58String], {
    active: bigint;
    legacy_claimed_rewards: number;
    stash: SS58String;
    total: bigint;
    unlocking: {
        era: number;
        value: bigint;
    };
}, true>

Map from all (unlocked) "controller" accounts to the info regarding the staking.

Note: All the reads and mutations to this storage MUST be done through the methods exposed by [StakingLedger] to ensure data and lock consistency.