feat(cb2-13154): Provide a '‘centralDocs'' object for VTx

[Daniel-Searle]

Provide a '‘centralDocs'' object for VTx

1. This change is to add in the central docs object into the request and response types inside of test types.
2. All of the vehicle types schemas needed to be updated to include the central doc object as well as the PUT schemas.

• PSV
• HGV
• TRL
• CAR
• MOTORBIKE
• LGV

3. A new enum has been added that contains all of the test type id's that require a central docs object to be present.
4. New functions that are used to identify if a test type is a central doc test type and apply custom validation on the test type.
5. New integration test file, testing validation error messages.
6. Test result JSON files have been updated to include the new object for both of the appropriate requests and responses.
7. Added in new unit tests to validate that the new helper functions are functioning from a function level, as well as testing them in isolation.
8. Utilise the test type id's from the common repo same as the helper method.
9. Validation to throw an error, when the test type shouldn't have the central doc object.

CB2-13154

Checklist

• Code has been tested manually
• PR title includes the JIRA ticket number
• Branch is rebased against the latest develop
• Squashed commit contains the JIRA ticket number