Add feature flag to make Finance 2 user workflow optional

[fourthletter]

Description

Add a feature flag (in base.py) to set if finance 2 needs to approve invoices or if finance 1 can do it themselves.

Name it ´INVOICE_EXTENDED_WORKFLOW´, default too false.

Priority

• High (keeping you from completing day-to-day tasks)

Ideal deadline

October 2022

Dev Tasks

• Add new wagtail settings to make Finance 2 optional, with help text - All the permissions of Finance 2 will be transferred to Finance 1.
• ❓ where in the admin should we have this setting?
• If Finance 2 is optional, hide the UIs related to the Finance 2 role and update the logic to upgrade the permission of Finance 1 position.
• Add Tests - Settings Page, workflows.

[frjo]

Updated this issue to make it a feature flag not a removal.

[frjo]

One second thought an organisation who do not need the two steps (finance 1/2) for invoices can simply make all finance users finance 2. I think this is the cleanest solution.

[theskumar]

@frjo Update: I added the dev tasks in this issue.