[FIX] stock: replenishment flow

Usecase to reproduce:
- create a product with 0 stock
- Sale order 500 units
- a RFQ is created for 500 units
- in replenishments, you have 0 units to order, OK
- RFQ --> confirm PO
- in replenishments, now the quantity to order is 500
--> should still be 0, it leads to confusions

It happens because the replenish action check the missing
quantity for today. It result by -500 units since the delivery
is planned for the next day (default supplier lead days = 1).
But since the orderpoint exist, the quantity forecasted is
already computed correctly with the right lead time.

But the action will remove the 500 missing today from the
quantity forecasted (The idea is to add the missing quantity on
the main location. e.g. I have
-10 units in WH/Stock/Shelf1
-20 units in WH/Stock
The orderpoint will only look for its own location -> 20 to reorder
The replenishment report look by warehouse and not by location -> 30
missing. So 30 missing + 20 incomming -> 10 to add (by default on
WH/Stock)

The fix is to add a step when a product is missing then compute its
virtual available with lead days (to avoid missing confirmed moves
during the lead time).

opw-2456978

closes odoo/odoo#69527

X-original-commit: f939c7b2
Signed-off-by: Arnold Moyaux <amoyaux@users.noreply.github.com>