Add Organizations::Stateful concern with state machine
## What
Introduce an `Organizations::Stateful` concern modelled after `Namespaces::Stateful`, but stripped of concepts that don't apply to organizations (ancestor inheritance, archival, transfers, state preservation).
## States
| Value | Name | Description |
|-------|------|-------------|
| 0 | `active` | Default. Organization is fully operational. |
| 1 | `deletion_scheduled` | Soft-deleted. Invisible to non-admins. Reversible. |
| 2 | `deletion_in_progress` | Hard-deletion worker is running. |
## Implementation plan
See https://gitlab.com/gitlab-org/gitlab/-/merge_requests/230909+s.
issue