Refactor Step scheduling

[johipsum]

We need to save the step-scheduling-configuration separately and not as a part of configParams. configParams should only hold information about the step payload. Scheduling-configuration should be part of scheduling

{
  ...,
  configParams: [{ ... }, { ... }],
  scheduling: {
    startDatetime: <ISODateString>,
    interval: <Number>,
    intervalType: <MINUTES || HOURS || DAYS>
  }
}

Besides that we need to enhance the flow object with the triggerType parameter. triggerType can be

• MANUAL (default),
• AUTOMATIC and
• SCHEDULED

---

Tasks:

• [x] move scheduling-configuration from configParams to scheduling
• [x] add triggerType to to flow
• [x] make it possible to add a startDatetime

[johipsum]

related to https://github.com/kreuzwerker/DKT.flows/issues/60