Provide an official permit2 distribution to the npm package registry

[PaulRBerg]

There seems to be no official npm package associated with this repository:

https://www.npmjs.com/search?q=%40uniswap%2Fpermit2

Only an @uniswap/permit2-sdk package, but that's a front-end library.

The lack of a Node.js package is not great for:

• Non-Foundry users, e.g. Hardhat
• Foundry users who, for whatever reason, prefer to use Node.js's dependency management system over git submodules
• Projects building on top of Permit2 which want to ship a Node.js package and include permit2 as a peer dependency (e.g. the project I represent, Sablier)

Providing a package should be as simple as adding a basic package.json file, and running npm publish.

Related:

• Add an official forge-std distribution to npm foundry-rs/forge-std#170
• feat: add package.json foundry-rs/forge-std#176