[FIX] {purchase_,}stock: recompute orderpoints on SM's date change

Updating the scheduled date of a delivery doesn't update the quantity to
order of an orderpoint

To reproduce the issue:
(Need purchase)
1. Create a storable product P with a seller
2. Create and confirm a planned delivery D with 1 x P
3. Open the replenishment page
    - There should be a line for P (Forecast: -1, To Order: 1)
4. Edit D and postpone the scheduled date
5. Go back to replenishment page

Error: The line is still present, its forecast qty is correct (0) but
the quantity to order is still 1 (instead of 0)

`qty_to_order` is a stored field, so when loading the replenishment
page, its compute method is not called. Moreover, even though
`qty_to_order` depends on `qty_forecast` and the compute method of
`qty_forecast` is called, it still won't trigger the compute:
when setting the value of `qty_forecast` from its compute method, it
will lead to:
https://github.com/odoo/odoo/blob/b54f78de307543efcea934206806f361eaac811a/odoo/fields.py#L1106-L1109


So, as shown and explained, we bypass the `write` of `BaseModel` and
skip the business logic and the recomputations

The compute of `qty_to_order` should actually be triggered earlier: when
we edit the scheduled date (step 4). That's the reason why this commit
adds a dependency to the compute of `qty_forecast`: it makes more sense
and becomes an implicit dependency of `qty_to_order` -> update the
scheduled date will trigger the compute of `qty_to_order`

OPW-2868167

closes odoo/odoo#93889

Signed-off-by: William Henrotin (whe) <whe@odoo.com>