Add --from option to vm.py, to generate Vm.sol from json file

[Tudmotu]

Defaults to "foundry-rs" and "master" respectively to maintain backwards-compatibility.

Added the --from option which lets you specify a local json file to generate Vm.sol from.

This PR uses argparse to implement the argument handling.

When running vm.py -h will display help information:

Running the script with no args should behave same as before.

[mds1]

Can you describe your use case for this? Also cc @DaniPopes who wrote the script originally

[DaniPopes]

It would be much easier to have just one argument that's the path of cheatcodes.json

[Tudmotu]

@mds1 yes, my use case is that I like to open the Foundry Book and Forge-Std PRs before the main PR on Foundry gets merged. The reason I do it like this is because I have very little time to actually write code so when I have the opportunity, I try to get everything done all at once.

This means that in order to update the Vm interface using vm.py, I need to manually edit the CHEATCODES_JSON_URL to point to my feature branch on my Foundry fork.

Adding these params lets me run e.g. ./scripts/vm.py tudmotu vm.mockCalls and it'll be updated based on my feature branch.

[Tudmotu]

It would be much easier to have just one argument that's the path of cheatcodes.json

You mean provide the entire URL on the command line?

[DaniPopes]

No, a path to a file, defaulting to fetching from the default source and keeping it in memory

[Tudmotu]

No, a path to a file, defaulting to fetching from the default source and keeping it in memory

Oh, so for example vm.py --from /path/to/my/cheatcodes.json?

[mds1]

Thanks @DaniPopes

@Tudmotu I can review + merge once that change is made!

[Tudmotu]

@mds1, @DaniPopes , updated the PR with the --from flag