Bundle TypeScript type definitions with the package

Many Javascript libraries these days include TypeScript definitions. There are third-party better-sqlite3 TypeScript definitions available[1], but they are difficult to use. They aren't well documented, and some of the design choices seem ... odd. Since they are hosted within a general definitions github project, there is not a convenient place to ask questions or build a community. They are getting 5k downloads per week, so there is an audience for them.

It would be great to have official TypeScript support, and documentation.

[1] https://www.npmjs.com/package/@types/better-sqlite3