Load assets with Mix or Vite instead of a CDN

[LukeTowers]

Replace #3 by pulling in the dependencies via NPM and compiling with Mix or Vite instead.

[zhaobenny]

Will try working on this!

[zhaobenny]

It doesn't seem quite feasible to complie the ckeditor4 dependency into a single file / smaller number of files (the official webpack template doesnt really show this too..)

The final build files if added to git are nermous and similar to #3

[LukeTowers]

@zhaobenny that's fine, at least they'll be easier to update in the future.