KvListSelector:
    | { prefix: KvKey }
    | { prefix: KvKey; start: KvKey }
    | { end: KvKey; prefix: KvKey }
    | { end: KvKey; start: KvKey }

KvListSelector is used to select a range of keys from the database.

The selector can either be a prefix selector or a range selector. A prefix selector selects all keys that start with the given prefix (optionally starting at a given key). A range selector selects all keys that are lexicographically between the given start and end keys.