ethers-ens set-content does not support IPNS hash

[wighawag]

Describe the bug
trying to set an IPNS hash as content fails with Error: Non-base58 character

Reproduction steps
ethers-ens set-content name.eth k51qzi5uqu5dmgyzzlivmvyqkhv2zj8zth8vpmvqvihontt72p32aaybc83fqc

Search Terms
ipns

[ricmoo]

I do believe it only handles base58 currently. I am moving the cli out into an ancillary package and can make this change then.