feat: add create-genesis-bls cmd

[gitferry]

This PR is to add gentx cmd, which generates a BLS key file that consists of {address, bls_pub_key, pop, pub_key}. An example of running this cmd is babylond gentx --home ./ where --home is optional and indicates the root path of babylond node with ~/. as the default value.

The pre-conditions of running this command are the existence of the node keyring, which can be generated via babylond init or babylond testnet, and the existence of the BLS key, which can be generated via babylond create-bls-key.

This command will produce a json file in [path-to-babylond]/config/gen-bls-[validator_address].json like the follows:

{
  "validator_address": "bbnvaloper1eppc73j56382wjn6nnq3quu5eye4pmm06uv5pk",
  "bls_key": {
    "pubkey": "gANrHkyFtbwTxvzR3qYxJ6k02sE1ffzN8qhA2GmEstlwptAmnDBtS1Amd9c6cq4vBWtMYaZeQdFmc+Vik8R5brM0HUC2EasVWvKyAUqe3fK6494xZZIcMyHSd+un7MhT",
    "pop": {
      "ed25519_sig": "rWBgzsgCVjFzAkgt0KPFGD+8NONwFYgn0XzI1TsvdhbFHO0dEMaXYhcMOBlAAUGcRdxkEaFdCp4QhKu7LWBQBg==",
      "bls_sig": "mQGCZ32N1+HKwaLLCZ5Bqs93269OILhutJYgoEG6FMCbGBr3tHJ7T/jg7ORWg2c+"
    }
  },
  "val_pubkey": {
    "key": "C4oza8JummU2nTlyp/qnohXmJws/yFzPVoPsldub0ag="
  }
}

[vitsalis]

Amazing 👏

[vitsalis]

Should we also verify that the POP is a valid one?

[gitferry]

Nice spot! I have added a Validate() method into GenesisKey and the method is called when GenesisKey is first loaded from the file.