Add ability to rename keys through the CLI

[adrianbrink]

It would be great if it's possible to change the name of the keys in the CLI.

[rigelrozanski]

should be a part of gaiacli keys update

[jackzampolin]

I don't think this feature is needed. You can always reimport the mnemonic under another name if it is absolutely necessary.

[alexanderbez]

Doesn't seem like a good UX @jackzampolin. I don't see any harm in keeping this open. It's a good first issue.

[julienrbrt]

Implemented by #9601