[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
Is it necessary to have such complicated routes ? /slides/my_channel:42/view/my_slide:98/like ? Shouldn't it be /slides/my_slide:98/like ? Anyway form a slide you should always find its channel back.

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