[IMP] openacademy: Set form fields to readonly based on workflow states

[KarenKawaii]

VX#5845

There are two options to do this:

• Modifiying the view.
  • Adding the attrs readonly into the field that you want.
  • However, this only applies into the modified view.
• Modifiying the fields in the model.
  • Adding a method that returns a dictionary with the attribute values for key-state, e.g., no_editable_states.
  • Then, add the attribute states=no_editable_states into the fields of your model.
    This is a better approach if you don't want to change the views one by one
    because your are modifying the model's fields.