[FIX] pos_restaurant : put jquery.event.drag-2.2.js in 'asset_backend' b...

...undle to remove the 'prevent clicking on t-field' behaviour on frontend

Task: https://www.odoo.com/web#id=11271&view_type=form&model=project.task&action=327
Pad: https://pad.odoo.com/p/r.QghWc21ufpzCAYWk
I don't think following assets are used in frontend, why not simply change assets_common to assets_backend, are these assets used in frontend ?