fix(Multicall): use correct assembly for revert bubbling

[penandlim]

Related Issue

N/A

Description of changes

The implementation taken from stackoverflow uses incorrect assembly.

Since the first 32 bytes of bytes memory result will be the length as uint256, only adding 4 to the pointer makes the Error(string) signature (0x6408c379a0) as the length, which is incorrect. See tests here

This medium article by @0xdeadbeef0x goes over the possible things that can go wrong with this exact implementation:
https://medium.com/@0xdeadbeef0x/the-double-edged-sword-of-abi-decode-f81529e62bcc

Therefore the correct way is to add 32 and revert the data with the length specified.

Also this solution works for both string style (revert("reason"), require(false, "reason")) and custom error style revert CustomError(), making the code cleaner.

[snreynolds]

something like this has already been implemented, thank you for raising this!