Switch & upgrade to quickjs-ng 7.0.0

[p-bakker]

quickjs-ng 7.0.0 has been released, so would be nice to update this project to that version

Additionally, it seems that quickjs-ng has much more traction than quickjs, so maybe make quickjs-ng the default?

[justjake]

I don’t know how CMake works, so I’m reluctant to add a dependency on CMake to this project. If you want to maintain the quickjs-ng variants I’m happy to accept a PR updating the build process to work with quickjs-ng 7