Admin, create new order: distributor and order cycle are now mandatory on step 1 (aka the set_distribution step)

[jibees]

What? Why?

• Closes Backoffice orders: Endless spinner and error 500 after skipping OC selector  #6133

Context: Admin section, creating a new order

This PR make the distribution step (ie. the one that set both distributor and order_cycle for an order) mandatory when creating a new order in the admin backoffice.

• creates a new step, via a new URL: /distribution
• validates order_cycle and distributor presence for an order in a set_distribution_step context
• remove links to others steps on /distribution when no distributor or order_cycle are set

Can't access next step-s (via Next button, or links on the side) until distributor and order cycle are set

Can access next steps when distributor and order cycle are set

What should we test?

As an admin, check that when creating a new order, we can't go to next steps until distributor and order_cycle are set for this new order

Release notes

Changelog Category: User facing changes

The title of the pull request will be included in the release notes.

Dependencies

Documentation updates

[mkllnk]

Great work. There's just one suggestion below.

[rioug]

Looks good 👍

[drummer83]

Hi @jibees,
Thanks for this one!

I have reproduced the issue before staging first. The situation is a bit different now, because when the issue was created, we still had the product selection first and then the customer selection afterwards. This is the other way round now. Additionally the customer selection doesn't return any results if no distributor is selected on the very first step.
The good thing is: Both issues are solved by your PR because there is no way to access the next pages without selecting distributor AND order cycle.

If information is missing, one of the following errors will be shown:

I didn't manage to see any endless spinners of error 500. Excellent!
Merging! 🥳
Thanks!