Method to extract names of existing Project, Profile, or Task variables

I think it would be very helpful for there to be an action to get the names of Project, Profile, and Task variables.

The action settings would have the user indicate whether they want to get a list of the Project, Profile, or Task variables. By default, the action would get the variables from its local context, but an option could be added to get variables from a named profile, project, or task.

By default, the action would return an array of those variable names, but a checkbox could enable returning a JSON object containing the variable-value pairs.