Provide an official permit2 distribution to the npm package registry

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

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.

Uniswap / permit2