Returns filterable list of validators with their balance, status and index.
Information will be returned for all indices or public key that match known validators. If an index or public key does not
match any known validator, no information will be returned but this will not cause an error. There are no guarantees for the
returned data in terms of ordering; both the index and public key are returned for each validator, and can be used to confirm
for which inputs a response has been returned.