Feature request: improve key output

[mdyring]

Currently tmkms yubihsm keys list outputs key information in hex format, that is hard to reconcile or use.

I'd like to suggest the following changes:

1. Output the key label in tmkms yubihsm keys list to make intended use obvious.
2. Introduce a tmkms chains list command that outputs keys in the expected format (bech32). It could display the chain-id, and then the formatted list of associated keys.

[tarcieri]

The output was originally a bit better for cosmos, but regressed in #205. It'd be nice if it used chain-specific formatting logic if available.

[tarcieri]

I closed this in #275, implementing something close to the behavior before #205, which is to list keys in Bech32 with chain-specific prefixes when the configuration allows for this.

It should hopefully work almost all of the time, provided the KMS is properly configured. In the event it isn't, it will fall back on the hex representation (i.e. the current behavior).

[mdyring]

Cool, thanks!