Related to nim-codex/457, nim-codex/458.
To cover the entire SlotId (uint256) address space, each validator must validate a portion of the SlotId space. When a slot is filled, the SlotId will be put in to a bucket, based on the value of the SlotId and the number of buckets (validators) configured. Similar to `myRequests` and `mySlots`, a function called `validationSlots` can be used to retrieve the `SlotIds` being validated for a particular bucket (validator index). This facilitates loading actively filled slots in need of validation when a validator starts.