Sample gentx for Agoric testnet

gentx.json

```json
{
  "body": {
    "messages": [
      {
        "@type": "/cosmos.staking.v1beta1.MsgCreateValidator",
        "description": {
          "moniker": "foo",
          "identity": "",
          "website": "",
          "security_contact": "",
          "details": ""
        },
        "commission": {
          "rate": "0.100000000000000000",
          "max_rate": "0.200000000000000000",
          "max_change_rate": "0.010000000000000000"
        },
        "min_self_delegation": "1",
        "delegator_address": "agoric1z8rldx498tf49p5ze04jhakyumkh7vyxku7e0p",
        "validator_address": "agoricvaloper1z8rldx498tf49p5ze04jhakyumkh7vyxxydsnq",
        "pubkey": {
          "@type": "/cosmos.crypto.ed25519.PubKey",
          "key": "KYRAZyBOGm1N48XB0QZ0/mCgDp0mqvvkkqZfiNDzUjk="
        },
        "value": {
          "denom": "ubld",
          "amount": "50000000"
        }
      }
    ],
    "memo": "eee6a8aa4a564344a7673ad4979e4eacab96d351@172.16.1.78:26656",
    "timeout_height": "0",
    "extension_options": [],
    "non_critical_extension_options": []
  },
  "auth_info": {
    "signer_infos": [
      {
        "public_key": {
          "@type": "/cosmos.crypto.secp256k1.PubKey",
          "key": "AsTq/F4kro8D8nJfIHSWloBa3uXITd1MHuP7G5rwn7mv"
        },
        "mode_info": {
          "single": {
            "mode": "SIGN_MODE_DIRECT"
          }
        },
        "sequence": "0"
      }
    ],
    "fee": {
      "amount": [],
      "gas_limit": "200000",
      "payer": "",
      "granter": ""
    }
  },
  "signatures": [
    "6VV/bFehysQR7x8WMcd0nqodvFGwYS7aTMe2UEMGH99rRM7Us57zp+DWHu5GJM/rn3VzG5xnR5FSrsLqf0Ew7A=="
  ]
}
```