[16.0][MIG] rotordc_autofill_product_variant: migration to 16.0

[huguesdk]

odoo task

t12917

[polchampion]

functionaly tested on rotor-v16-test, partial success:

• weight
• volume and dimensions
• internal reference [EDIT : it works]

test report: the internal reference is only copied for the firest variant created. In v16, there is a non-blocking warning when adding an internal reference that is already used. Maybe that's the reason why the internal reference doesn't get copied to variants beyond the first one.

[polchampion]

functionaly tested on rotor-v16-test, partial success:

* [x]  weight

* [x]  volume and dimensions

* [ ]  **internal reference** [EDIT : it works]

test report: the internal reference is only copied for the firest variant created. In v16, there is a non-blocking warning when adding an internal reference that is already used. Maybe that's the reason why the internal reference doesn't get copied to variants beyond the first one.

@huguesdk I actually had tested without installing the module. Weight and dimensions are copied anyway, so idk if this part of the code is relevant. Internal reference is copied correctly.

[polchampion]

successful functional test

[huguesdk]

@polchampion thanks to you i discovered a bug in product_dimension (OCA/product-attribute#1811) and simplified the code of this module.