Other: Map Value action - when the result is a single value, do not return an array, just return the value

Other: Map Value action - when the result is a single value, do not return an array, just return the value.

This allows other actions which only accept a single value, to use the result of the Other: Map Value action as an input.

For example, when setting the payment instrument on a Contribution. Without this change the following error is thrown: "error_message": "Action Create Contribution failed. Caused by payment_instrument requires a single value a multiple value is given"

This is a similar approach to !91 (merged)

Agileware Ref: CVAP-28