feat: add gas price RPC methods

[jinoosss]

Descriptions

Add an RPC endpoints to get the transaction's gas fee based gas price.

The price of gas provides low, average, and high values for each denomination of the coin.

Gas Price Endpoints

getGasPrice

Retrieve gas information by coin for a block range.

• Params: If empty, it defaults to a range of 1,000 blocks from the latest block.
  • from block height (number)
  • to block height (number)
• Response: List results for gas prices with low, average, high, and denom.

Example request:

{
  "id": 1,
  "jsonrpc": "2.0",
  "method": "getGasPrice",
  "params": [100, 200] // If parameters are empty, the default is latest 1,000 blocks
}

Example response:

{
    "id": 1,
    "jsonrpc": "2.0",
    "result": [
        {
            "low": 40000,
            "average": 50000,
            "high": 70000,
            "denom": "ugnot"
        }
    ]
}

subscribe

• newGasPrice - fires a notification whenever a block with a new transaction is added to the chain.

Example request (over WS):

{
  "id": 1,
  "jsonrpc": "2.0",
  "method": "subscribe",
  "params": [
    "newGasPrice"
  ]
}

Example response when a newGasPrice event happens (over WS):

{
    "params": {
        "result": [
            {
                "low": 70000,
                "average": 70000,
                "high": 70000,
                "denom": "ugnot"
            }
        ],
        "subscription": "eb654246-a1c4-4ef2-9d99-42e1308ee68f"
    },
    "jsonrpc": "2.0",
    "method": "subscription"
}

---

Related Issue

• [chain] Gas Estimations gno#1826
• fix: Modify app path method to simulate for ABCI query gno#3207

[zivkovicmilos]

Looks good 💯

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