get_control.RdPulls values from the control tibble by name; convenience function for working with the control tibble.
get_control(this_control, control = workflow_controls)is the string containing the control of interest
defaults to workflow_controls; is a tibble containing columns R_name and Value,
The value of control$Value when control$R_name==this_control; typically will be a character, frequently requires coercion to other types.