[FIX] web_editor: fix _view_get infinite recursion

The _view_get function is a recursive function used to retieve all the
views related to a view (inherited or t-called).

The issue is that by an odd set of circumstances it is possible to have
a loop in the view graph. Resulting in the recursive function being
called until a "maximum recursion depth exceeded" error occurs.

Example of a loop: A t-call B and A inherit from B

This is possible on an update of a view that has been forked by website:
If the view A was doing a t-call on B and is has been duplicated with
the arch modified.
When we update with the changes A now inherit from B instead of t-call B
Since the arch was modified it will not be updated so A will still
t-call B but the inherit_id of A is unchanged so it will be updated to
reference B resulting in a loop.

closes odoo/odoo#51620

X-original-commit: 63e1e84e
Signed-off-by: Jérémy Kersten (jke) <jke@openerp.com>