Before this commit, there is no verification while changing a product's
company. That can lead to issue where some operations cannot be done
because of access errors.
To avoid that, this commit prevents to change the product's company if
some quants for this product exist in another company's location.

How to reproduce:
- Have at least two different companies (let say CompA and CompB);
- Create a new product who belong to no company;
- For this product, add quantity on hand in a CompA location;
- Now, change the product's company for the CompB;
- While selected only the CompA, go into the Inventory Adjustments and
  try to create a new inventory adjustment for the CompA location with
  this product's quant -> Access Error.

opw-3095984

closes odoo/odoo#110690

X-original-commit: c123220e
Signed-off-by: Tiffany Chang <tic@odoo.com>