[16.0][ADD] mrp_subcontracting_serial_mass_produce

[nobuQuartile]

Summary

• When using Mass Produce on a subcontracting MO with serial-tracked finished
  products, the standard flow splits the MO and assigns serials but does not
  call subcontracting_record_component() on each split MO. As a result,
  subcontracting_has_been_recorded remains False and the finished serials are
  never synced to the receipt move lines.
• This module extends stock.assign.serial._assign_serial_numbers() to
  automatically call subcontracting_record_component() on each split MO
  after Mass Produce, enabling Mass Produce to work end-to-end for
  subcontracting orders.

@qrtl
QT6138

[AungKoKoLin1997]

I think the current module is missing a CONTEXT.md. It should explain how this module fills a gap in standard Odoo behavior when the subcontracting operation type is unarchived, even though that is not the default Odoo setup.

I also do not think the module should be limited to mass production with multiple serial number entries. While the module mainly targets clunky serial assignment, it should also support manual serial number entry in the MO form, likely through an extension of _onchange_lot_producing.

Also, shouldn’t we propose this to OCB instead of creating a new custom module? Although the subcontracting operation type is archived by default, the issue still appears when a user unarchives it and performs operations on a subcontracted MO.