feat: publish forge-std to NPM under @foundry-rs/forge-std

Hi there 👋

It would be super awesome if there was an official `forge-std` on NPM.

There is a related issue pertaining to Hardhat ( https://github.com/foundry-rs/forge-std/issues/39 ), but my motivation is mostly around avoiding the need for submodules. I know I should learn to love submodules, but I am already happy enough with yarn / package.json for dependency management. My other dependencies already have official distributions, e.g:

- [Open Zeppelin](https://www.npmjs.com/package/@openzeppelin/contracts)
- [@prb/math](https://www.npmjs.com/package/@prb/math)
- [@prb/test](https://www.npmjs.com/package/@prb/test)

It would be super awesome to have `forge-std` there too 🙏