Add ability to populate lists/dropdown

[adiclepcea]

We would like to have a list or a dropdown that can be populated.
One possibility would be to have a textbox and when a button is pressed, the value in that textbox to be added to the list.
Another possibility is to have a dropdown where we can add values.
This would be needed so that we can create for example a list of users to be created automatically. This list would contain the users.