Plan order use earliest start date in resource plan instead of suggested start date

Summary:

Our client is using process manufacturing and they don't stop manufacturing unless absolutely have to (scheduled maintenance or running out of space to store FGs). They will have sales order come in but they want to keep making products and reduce machine idle time.

For example, today is 7/12. There are sales order they need to ship out 7/12, 7/13, 7/14 that they already have enough onhand of the products.

Sales order with scheduled ship date of 7/15, and 7/16 don't have enough onhand and so plants will need to make new products. When supply planning is run, planning will have plan work order with suggested start date of 7/14 to make products for 7/15.