[FIX] web_unsplash: unsplash images added on website break on products

Before this commit, selecting an unsplash image on website, then going
on a product page and selecting that same image in the media-dialog
would not work, and upon saving, the image would be the image
placeholder.

A previous fix in odoo/odoo#31328 added handling so that you could
choose unsplash images for a product, but it failed to account for
unsplash images that had already been added on a public view (for
example on a website page), which the user can choose in the
media-dialog.

This was caused by the fix only searching for the unsplash attachment on
the current model, and not among public attachments, resulting in an
empty search result.

This commit fixes that by adding that the attachment we are looking for
should either be on the current model, or be a public attachment.

closes odoo/odoo#49937

X-original-commit: 196d6b1630fa443bc1d143f76f62f7a719ca4930
Signed-off-by: Jérémy Kersten (jke) <jke@openerp.com>
Signed-off-by: Quentin Smetz (qsm) <qsm@odoo.com>

addons/web_unsplash/models/ir_qweb.py

@@ -19,8 +19,10 @@ class Image(models.AbstractModel):
                 res_id = int(res_id)
                 res_model = model._name
                 attachment = self.env['ir.attachment'].search([
+                    '&', '|', '&',
                     ('res_model', '=', res_model),
                     ('res_id', '=', res_id),
+                    ('public', '=', True),
                     ('url', '=', url_object.path),
                 ], limit=1)
                 return attachment.datas