This fixes:
```
DEPRECATION WARNING: Passing an argument to force an association to
reload is now deprecated and will be removed in Rails 5.1. Please call
`reload` on the result collection proxy instead. (called from
can_own_more_enterprises? at /usr/src/app/app/models/spree/user.rb:112)
```
This method in particular gets called a lot of times so it'll have it's
cost in performance.
For some reason the order objects were stale here when calling order.update! from either a payment or shipment callback, which was overwriting those states as nil on the order.
This new class lets us [Branch by
abstraction](https://www.martinfowler.com/bliki/BranchByAbstraction.html)
by encapsulating an order's balance. As a result, that's the only place
where we need to check the feature toggle, instead of every place where
`#outstanding_balance` is called (quite some). That would be very hard
to review and it'd be more likely to introduce bugs.
What I like about this is that we also managed to group together the
data and logic that we had spread in a few places and have it nicely
encapsulated. So, where we had a number, we'll now have an object.
Once we fully change all `#outstanding_balance` consumers to use this
new abstraction we'll be able to remove the methods this class replaces.
These are: `Spree::Order#outstanding_balance?`,
`Spree::Order#display_oustanding_balance` and
`OrderHelper.outstanding_balance_label`.
This is just the first step. I'll follow this up with a PR per
page/mailer/whatever where we use the balance to replace it with an
instance of `OrderBalance`. That is, splitting up what I explored in
https://github.com/openfoodfoundation/openfoodnetwork/pull/6959 but in
very small and manageable pieces.
- Use a new class to specify css customization
- Add to `line_item.rb` a fake method: `unit_price_price_and_unit` @andrewpbrett will change it with real values.
- Add a new variable: $text-xs to specify small font-size
squash "Display unit price on /cart page"
Rails 5 introduced some breaking changes to these built-in methods, and the new versions no longer work correctly in relation to decrementing stock with VariantOverrides.
