Implement adding data from validation function (condition)

[develop-cs]

Is your feature request related to a problem? Please describe

In some use cases, input_data can be a data set and some conditions being based on a computed value (e.g., a mean).

Currently, if you want to use this computed value in your action (e.g., throwing an alert "The mean XX is out of range [YY - ZZ]") you simply can't because data adding from a validation function wasn't designed.

Describe the solution you'd like

Allow validation function implementations to add some data in the input_data argument with an identified prefix (e.g., output.mean). Thereby, an action function implementation (or another validation function) will be able to get it later.