Added a flag indicating if this prison is to implement the API flow.

[#81200540]
* Moved _ad_help to the views/application directory to be reusable across the app.
* Added a form for editing prisoner's information.
* Added a guard around the logic in PrisonerDetailsController to ensure that the client
  has their cookies enabled.
* Moved helper methods to a ParamUtils module.

[#81200540]
* Added a blind stopper™ in a few places.

[#81200540]
* Added session initialisation to PrisonerDetailsController.

[#81200540]