Implement estimate_gas for EVM smart contracts.

[MathieuDutSik]

The function estimate_gas of Ethereum allows for estimating the gas being used for the run. It allows us to know how much gas is needed.

There is no standard that needs to be followed, and both 0 and u64::MAX could be put without breaking anything. Yet, it is useful to give a reasonable value.

We can use the handle_query for that functionality since it does not modify the state. It will not work if that EVM smart contract calls a Wasm smart contract since the Wasm does not have an estimator of gas usage.