feat: add npm package + config files

For #1 (closed)

What does this MR do?

Adds package.json and config files.

1. Run npm run build to compile tsc
2. Run npm pack to then make a tarball

Checks

1. Code builds and compiles
2. Pipeline passes
3. I checked that the tarball is installable using npm i /path/to/tarball in a fresh package, then tried importing it. No linting warnings etc. from VSCode