[FIX] website: filter filter_opt of dynamic snippet by website_id

Add a filtering by the contextual website_id when looking up available
website_snippet_filters via an rpc route limited to logged in users but
relying on a sudo to actually obtain the list of available filters.

Before this commit filters were visible on the editor for all websites.

After this commit filters are only visible on the editor of the website
that matches their website_id.

https://github.com/odoo/odoo/pull/59341


task-2312878

closes odoo/odoo#59341

Signed-off-by: Jérémy Kersten (jke) <jke@openerp.com>