Show the Solidity line in the hevm warning regarding path building/exploration

[gustavo-grieco]

If the symbolic exploration is limited by the depth or width, or some limitation of the tool, considering showing the specific line from the Solidity contract, if available.

At least show the file/line, or even better, include the complete line in the warning (perhaps using a verbose flag, if you don't want a very verbose output by default).

Short term, this will allow to debug faster any hevm issue and know exactly what was explored or not. As a long term effect, smart contract developers will be more aware of the complexity of their code, in particular, if they want symbolic execution to correctly explore all the possible path to verify some property.