Changing Dynamic Discounts for SyrveCard via API

The ability to set and modify dynamic discounts for SyrveCard in orders via the API has been added.

The new method ChangeOrderSyrveCard5DynamicDiscounts allows plugins to modify dynamic discounts for SyrveCard in orders.

Previously, the property DynamicDiscounts was read-only, and there was no way to programmatically change these discounts. This complements existing methods such as ChangeOrderAppliedSyrveCard5ManualConditions and ChangeOrderSyrveCard5Coupon.