This commit removes the last low level legacy stuff (e.g. Widget,
mixins...) from the backend bundle, and from the webclient bundles
of mrp_subcontracting and project. They are no longer used in the
backend. There're still necessary for the frontend and for the
web_editor though, so we had to manually add them in the lazy
loaded bundle of the editor. Hopefully, the last widgets and
dialogs will be converted soon, and we'll finally get rid of all
those legacy files.
Part-of: odoo/odoo#139154
Aaron Bohy
85372ffa94