The instructeur, dossier and claimant where created regardless of
wether they already existed or not.
With this commit:
- Associations are declarated in a more idiomatic way
- They are correctly not created if they are provided when creating the
object.
Now that all states have a dropdown, we can simplify the code.
This also brings the "Repasser en instruction" action for all states
(including when no attestation or motivation is present).
- Fix the missing link to see attestations (see #4400)
- Fix the "Repasser en instruction" wording being confusing for
accepted state
- Add lot of tests
