Add tests for Don and PaymentDonation, which had no test coverage
yet: create/fetch/update/delete, the draft -> validated -> paid
status workflow (setValid/setPaid) and a separate self-contained
cancel test (set_cancel() has no status precondition, unlike
setValid()/setPaid()).
Note: create() never writes $this->status to the fk_statut column
(it always defaults to draft in DB) even though initAsSpecimen() sets
status=1 in memory - the test re-fetches to check the real status.
PaymentDonationTest also cross-checks Don::getRemainToPay() after a
full payment: unlike Tva::addPayment()/getSommePaiement() (see
TvaTest.php), PaymentDonation::create() and Don::getRemainToPay() do
agree on the same fk_donation link, so this is a genuine regression
check, not a workaround.
The module is auto-activated in setUpBeforeClass() if not already
enabled, following the same pattern as the other recently added
tests (activation is real and persists after the test run, it is not
undone by the rollback in tearDownAfterClass - see comment in
setUpBeforeClass() for why).
Co-authored-by: Laurent Destailleur <eldy@destailleur.fr>
