[IMP] pricelist_refactor: support discounts and formula in pricelists for subscription and rental products

[vrgo-odoo]

Description of the feature this PR addresses:

• Enhances pricelist handling by introducing discount and formula support for subscription and rental products.

Current behavior before PR: Subscription and rental products did not support discount and formula-based pricing in pricelists.

Desired behavior after PR Discount and formula is added for subscription and rental products in pricelists.

[robodoo]