fix: support ints in cast

[mds1]

Currently this just modifies the clap config to allow hyphens for commands that can take negative values as input args. A sanity check that I didn't miss any commands would be appreciated.

Clap also has an option to allow hyphens globally, but only allowing them as-needed is preferable.

The commands with the "negative values not yet supported" comment still don't work due to ints not being supported somewhere in the underlying methods. Will get that fixed next before taking this out of draft

[mds1]

Taking this out of draft, and figured we could merge as-is and finish adding int support in a separate PR. In it's current form:

• This PR fixes cast abi-encode, which now works for both ints and uints
• The other modified cast methods still fail, like they did before. But instead of failing at arg parsing they fail internally

It'll be a bit until I find time to get the rest of the int support working, so figured it's not worth holding up the fix for cast abi-encode in the meantime

[mattsse]

lgtm,
could you create a followup issue with what we need to fix internally now that we can parse them correctly at the arg parse level?

[mds1]

@mattsse just created gakonst/ethers-rs#842 to track a useful ethers-rs improvement which would make signed int support simpler. Once that's done, I've documented what we'd need to do next in #29 (comment), where I'm tracking various unsupported cast features to avoid clutter from too many issues