Add types

[Shahaed]

Add types for this package. Simple type definition already exists: https://www.npmjs.com/package/@types/uuid. Incorporating it into this repo would be really helpful.

[ctavan]

This has been discussed in the past but as long as this library is written in JavaScript we're going to continue to publish the types as a separate package, see #368 (comment)

In fact the maintainers of uuid are maintaining @types/uuid as well!

[Shahaed]

Most other popular npm packages include types in the same package and saves typescript users from having to import 2 packages. Also makes maintenance easier.

My vote would be including types in the same package, but it's y'all decision.

[ctavan]

Feel free to raise this issue over at TypeScript. If TypeScript decides to change their recommendations, I'll be happy to follow whatever the official recommendations are.