[MIG] web_responsive: Migrate to v12 and refactor

This migration includes a full refactoring to make this module more
maintainable. Some things that have changed:

- Removed external libraries.
- Change Less for Scss.
- Reduce ES and XML to the minimal required needs.
- Implement as much features as possible with just Scss.
- Remove copyright from `__init__.py` files.
- Trigger the new hotkeys system from Odoo v12 with `Shift+Alt` instead
  of just `Alt`, and restore some good old hotkeys (`E` for "Edit",
  `D` for "Discard", and `A` for "Apps menu").
  See https://github.com/odoo/odoo/issues/30068 on the matter.
- Control panel breadcrumbs are collapsed into a single backwards icon.
- Add FA icons to most common buttons in control panel.
- Hide text in XS for those buttons, to have a slicker phone experience.
- Lots of gifs in the README!

web_responsive/models/__init__.py

@@ -1,4 +1 @@
-# Copyright 2018  Alexandre Díaz
-# License AGPL-3.0 or later (http://www.gnu.org/licenses/agpl).
-
-from . import inherited_res_users
+from . import res_users