[IMP] operating_unit: Different user default per company

[SirPyTech]

Allow a user to have a different default Operating Unit in each company.

[HekkiMelody]

Code review, LGTM

[github-actions]

There hasn't been any activity on this pull request in the past 4 months, so it has been marked as stale and it will be closed automatically if no further activity occurs in the next 30 days.
If you want this PR to never become stale, please ask a PSC member to apply the "no stale" label.

[SirPyTech]

Hi @OCA/accounting-maintainers, would anyone like to have a look? Thanks!

[AaronHForgeFlow]

I would prefer to introduce this major change on a newer version, perhaps v19

[github-actions]

There hasn't been any activity on this pull request in the past 4 months, so it has been marked as stale and it will be closed automatically if no further activity occurs in the next 30 days.
If you want this PR to never become stale, please ask a PSC member to apply the "no stale" label.

[SirPyTech]

I would prefer to introduce this major change on a newer version, perhaps v19

I understand, unfortunately we only needed this for 14.0.

Since we don't need this anymore, I'll save the bot some juice and close it already; hopefully someone who needs this will find it anyway.