fix(plugins): ckeditor now prevents image drag/drop/paste in editor

fixes #4970

code snippet is added as an external source, so it will not interfere with the default ckeditor code folder

TODOs:
 - [x] Change message to `fix(ckeditor)`
 - [ ] Move custom JS out of `vendors` and into an AMD file.
Even if i didn't write it myself? We are also not moving the other vendor files into views/default/js... i thought it was meant as a differentiation between own and foreign code...