Introduce Source Reservations (MSI Show delivery times per source and see source from which the product was sold)

Nobody has claimed this yet.

### Description (*)
Currently stock is reserved as a global qty from salable qty. There is no link to any source on order creation, but later in the process during shipment. For many merchants this is a problem and deviation from previous versions and M1. One option would be to disable source reservation #3076 but reservations are here to stay. A better solution is to add a source to the reservations.

The problem currently is:

- We need to know the stock source allocation at invoicing (or quote or order, but asap)
- We want to know the stock source allocation when customer is browsing the website to estimate delivery time

### Expected behavior (*)

Stock is allocated to the source during sale

### Benefits

Merchants need more specific reservations as exaplained above

### Additional information

Source reservations can be made as an option, turn on/off

Building blocks

- Product presentation: 'know' where it is coming from
- Order creation: assign stock reservation to source
- Shipment: nullify the reservation
- Additional: create method to change source allocation from A to B
- Credit memo/Cancel: revert reservations

Start by tracing the existing global reservation flow from order creation through shipment, then review each building block listed in the issue. Done should cover source allocation during sale, source visibility for delivery estimates, shipment cleanup, source changes, and reservation reversal on credit memo or cancellation, with the option to enable or disable source reservations.

Written by the indexing model from the issue text.