In property in for task should allow hardcoded arrays

[fjtirado]

Currently, in property in for task is expected to be a runtime expression that returns an array of objects to be used by the for loop.
It would be nice to allow the writer of the workflow definition to write the array there by himself.
The reason is currently an string is because in that particular spot it is assumed that specifying the whole array is not really useful in 99% of the cases, and that`s right.
But from schema point of view, it is more ubicuos to have (and it does not hurt in any case)

in:
    oneOf:
           - "type": "array",
              "items": {
                 "type": "object"
                }
          - $ref: '#/$defs/runtimeExpression'

rather than

  in:
              type: string
              title: ForIn
              description: A runtime expression used to get the collection to enumerate.

[cdavernas]

@fjtirado Even though I personally never encountered that specific use case, I don't see any reason not to support it.