[FIX] mrp: use correct UoM for each component in MO

In a Manufacturing Order, the components' quantities are rounded using
the rounding precision of the produced product's UoM. This leads to
incorrect values.

To reproduce the error:
1. In Settings, enable "Units of Measure"
2. In UoM, edit Units:
    - Rounding Precision: 1
3. Create two products P_finished and P_compo
    - P_compo's Product Type: Consumable
    - P_compo's UoM: L
    - P_finished's UoM: Units
4. Create a Bill of Materials
    - Product: P_finished
    - 1 Component:
        - Product: P_compo
        - Quantity: 0.2
        - UoM: L
5. Create a Manufacturing Order:
    - Product: P_finished
6. Confirm, Mark as Done

Error: Qty to consumes became 0 and consumed qty is 0. Both values
should be 0.2L, but they have been rounded using the rounding precision
of Units

OPW-2529462

closes odoo/odoo#71293

X-original-commit: aff3a2e0
Signed-off-by: Steve Van Essche <svs-odoo@users.noreply.github.com>
Signed-off-by: Adrien Widart <adwid@users.noreply.github.com>