[ADD] slides gallery module

- Task: https://www.odoo.com/web?#id=9093&view_type=form&model=project.task
- Pad: https://pad.odoo.com/p/r.QlQTvBv6mCcMrK4B
What is 'types' anyway ? Is it necessary to have this data when accessing a slide ? Sorting and searching when viewing a slide has a meaning or is it just to keep some data ?