Create a Cloudinary media source instead of a separate media type

TODO:

1. Allow inserting multiple assets at once (e.g. photogallery purpose)
2. Get rid of breakpoints configuration? (only used with custom render element, but not available as option in available field formatters, maybe we need to integrate it there)
3. Test with multiple stream wrappers e.g. simple image/file field type and cloudinary.[folder] steam wrapper.

I've added support of inserting multiple assets for the widget and form element

I've added a module to migrate from 2.x to 3.x, the module is ready to be reviewed

Automatically closed - issue fixed for 2 weeks with no activity.