Compose sub behaviours

[vishal-biyani]

Currently compose pre-built in some built in functions like foreach. For example the $.Tasks.DataValidator.Output in below workflow is always a list - which is list of individual outputs of DataValidator.

DataValidator:
    run: foreach
    inputs:
      foreach: "{ output('DataProducer') }"
      do:
        run: cpvalidator
        inputs:
          body: "{ task().Inputs._item }"
    requires:
    - DataProducer

CarpoolAllocator:
    run: cpallocator
    inputs: "{ $.Tasks.DataValidator.Output }"
    requires:
    - DataValidator

In some cases user may want to have a slightly different compose behaviour. For example instead of creating a list of outputs of DataValidator - you may want the CarpoolAllocator be called individually for each output.