SimpleParallelComposite should have action leaf as first child node

[Horryportier]

Is your feature request related to a problem? Please describe. I'm wondering is there an reason why this node can't have anything else than action node as first child. I've looked into code of the node and i can't seam to find reason why other types can't be used (although I'm not familiar with this code base). If there is an good reason for that then I would like to know why that is the case

Describe the solution you'd like SimpleParallelComposite that can run other types of nodes

Describe alternatives you've considered N/A

Additional context N/A