OrderItemPriceCalculationStrategy is not used on order modification

[kyunal]

Describe the bug
The OrderItemPriceCalculationStrategy used to adjust price calculation when items are being added or adjusted is not invoked on order modifications, specifically when a new item is added to the order during a modification.

To Reproduce
Steps to reproduce the behavior:

1. Use this tiny example strategy

import {
    Order,
    OrderItemPriceCalculationStrategy,
    PriceCalculationResult,
    ProductVariant,
    RequestContext
} from "@vendure/core";

export class TestOrderItemPriceCalculationStrategy implements OrderItemPriceCalculationStrategy {
    calculateUnitPrice(
        ctx: RequestContext,
        productVariant: ProductVariant,
        orderLineCustomFields: { [key: string]: any },
        order: Order,
    ): PriceCalculationResult | Promise<PriceCalculationResult> {
        return {
            price: 1337,
            priceIncludesTax: true,
        }
    }
}

2. Create a new order (draft or real) and add any item, it will have the price 13.37
3. Finalize the order, then modify by adding another (different) item
4. See error (the new item's original price is used)

Expected behavior
I would expect the OrderItemPriceCalculationStrategy to be used here as well.

Environment (please complete the following information):
Fresh installation with the @vendure/create tool

• @vendure/core version: 2.2.4
• Nodejs version: 20.12.2
• Database (mysql/postgres etc): SQLite

Additional context
This is potentially a breaking change as price calculation is handled differently.