Cosmos-sdk: gaiacli keys show <multisig> should show constituent pubkeys, and weights

[ValarDragon]

gaiacli keys show <multisig_key> should show constituent pubkeys, and their weights.

This would likely require adding a new multisig keytype to the keybase.

[cwgoes]

Additionally, gaiacli tx sign --validate-signatures with a threshold multi-signature should show which subkeys signed the transaction, and their weights, in addition to showing the validity of the composite signature.

[alexanderbez]

I can pick this up.

[alexanderbez]

Additional thoughts from @cwgoes:

• gaiacli tx multisign should check the multisig pubkey and see if the provided signatures are sufficient
• we need better confirmation of --chain-id in the CLI, it defaults to empty string sometimes