BiDiKo: Happy Path API-Tests

Akzeptanzkriterien

1. Accept Reply Test. Submission anlegen -> Reply anlegen -> Reply akzeptieren (zustelldienst!239)
2. Reject Reply Test. Submission anlegen -> Reply anlegen -> Reply ablehnen
3. Submission an vorhandenen Case anhängen Test. Submission anlegen -> Submission anlegen
4. 2 Replies in Case Test. Submission anlegen -> Reply anlegen -> Reply anlegen
5. Neuen /cases/* Endpunkt testen