Support Solidity panic codes in the RuntimeError class

Here revert reasons are processed. This currently only understands the revert strings (which have a signature of Error(string)). It would be nice to also support panic codes (with a signature of Panic(uint256)).

See https://docs.soliditylang.org/en/v0.8.0/control-structures.html#panic-via-assert-and-error-via-require for more information.

I think ganache should return panic codes as a numeric value for the moment.

[haltman-at]

FWIW, here’s the Solidity documentation of the panic codes, and here’s the table of panic codes that the debugger uses for interpreting them. 😃 (And which Truffle Contract would presumably also use if we added support for that there…)

[davidmurdoch]

Just realized this may be related to some changes plan to make to our eth_call error message strings that would provide additional information over what we give now. @MicaiahReid, I couldn’t find an issue for the new error strings we were talking about adding; they might all map to these specific panic codes.