[FIX] api, product: search by pricelist

- Activate variants and pricelists
- Go to Product > Products Variants
- Search for anything on the 'Pricelist' filter

A traceback is raised: 'Can only create cache keys from hashable
values...'.

This comes from the following change:

https://github.com/odoo/odoo/blob/4b06fe19fa68255b7982d15e5847da2f6d6209fd/addons/web/static/src/js/views/control_panel/control_panel_model.js#L962



It returns a list instead of a string. Since a list is not hashable, it
causes the issue.

There are not much solutions since the context key `pricelist` can be a
`list` or an `int` (an ID). We force the cache key conversion to a tuple
to avoid the `TypeError` and handle the `list` use case (which was
broken on top of crashing).

opw-2187757

closes odoo/odoo#45064

X-original-commit: ec0a8767143b4c4818418281803c4f52fefa8d2a
Signed-off-by: Nicolas Martinelli (nim) <nim@odoo.com>