[17.0][ADD] purchase_request: add constrains to check if a product is changed

[alan196]

This PR add a validation to check if a product is changed in a purchase order line.

If the product is changed and the purchase order line is related to a purchase request line, it will raise a validation error.

[alan196]

@marcelsavegnago I changed the commit description and rebase the branch

Could you help me to review 🙏

[HviorForgeFlow]

@marcelsavegnago I changed the commit description and rebase the branch

Could you help me to review 🙏

ping @marcelsavegnago