Introduce AAIB Reports

AAIB reports can now be created and edited within the system via SpecialistDocumentsController
Testing AAIB Report workflow

Refactored CMA helpers to be non specific for documents
Rename specific builders to reflect their actual class
Refactor doc_type into builder not the service

Instead of passing the document_type to the service allow the builder to decide the document_type
Move common CmaCase code to an abstract Document

Instead of duplicating code between CmaCase and AaibReport share the code in a Document class