Use ktor and kotlinx serialization

[rahulsainani]

What?

On top of #125 – Use ktor instead of retrofit and kotlinx serialization instead of gson for KMP support – Update MovieRepository to use ktor – Add ApiResponse to model different api responses to objects, this encourages mapping exceptions to objects at the edge of the system – Add safeRequest utility that maps to ApiResponse – Test updates

[rahulsainani]

@android10 Thanks for the review Fernando! 🙌 I agree about networking and rest of "core/lib" functionality being features but wanted to separate them into independent functionalities. We can also keep them in core and and see if we need to break them in the future or not. I'm open to your thoughts! :)