Given the denom, returns the authority metadata for the denom.
This method can receive both the denom encoded to URL (for the LCD requests)
and the denom not encoded:
e.g. factory%2Fterra1v0eee20gjl68fuk0chyrkch2z7suw2mhg3wkxf%2Futoken931
DenomAuthorityMetadata specifies metadata for addresses that have specific
capabilities over a token factory denom. Right now there is only one Admin
permission, but is planned to be extended to the future.