internal/ethapi: EstimateGas and Call handle revert error(#173)

[gzliudan]

in current version XDPoSChain, it always return message:

gas required exceeds allowance or always failing transaction

if solidity contract function reverts when metamask or other client calls method eth.estimateGas. So the user and wallet software can not judge if revert will occur, and can not get the revert message when revert. This is the main problem which complained by xcantera in #173. This PR parse and return the revert message/reason for both of eth.call and eth.estimateGas. I have tested this PR in my private network, not in Apothem testnet, since I can not synchronize with Apothem testnet according to current document.

Below is my test contract:

// SPDX-License-Identifier: MIT

pragma solidity ^0.6.0;

contract Test {
    uint256 private val;

    constructor() public {
        val = 1;
    }

    function getVal() public view returns (uint256) {
        return val;
    }

    function testRevert(bool willRevert) public view returns (uint256) {
        if (willRevert) {
            revert("I reverted");
        }

        return block.number;
    }

    function setVal(uint256 newValue) external {
        require(newValue < 10, "newValue >= 10");

        val = newValue;
    }
}

[wjrjerome]

Hi, is this an urgent fix ? If not, prefer merge against "dev-upgrade" branch. Otherwise we shall be ok with this merge into master as we can cherrypick into development branch

[gzliudan]

This is the fix for #173

Hi, is this an urgent fix ? If not, prefer merge against "dev-upgrade" branch. Otherwise we shall be ok with this merge into master as we can cherrypick into development branch

[xcantera]

Will be amazing if we have this fix asap :) Thank you for the work

[wgr523]

LGTM.
Pending dev-net test for this PR.

[AnilChinchawale]

PR would get live on the apothem network first...!!!