refactor(ocpp): extract version-specific logic from consumer layer

refactor(ocpp): extract version-specific logic from consumer layer

Move remaining version-specific logic from charging-station/ consumer
layer into the ocpp/ component:

- Create OCPPServiceFactory.ts with createOCPPServices() factory that
  instantiates version-specific OCPP services, removing 6 version-
  specific class imports from ChargingStation.ts
- Move createBootNotificationRequest from Helpers.ts into version-
  specific buildBootNotificationRequest methods in OCPP16ServiceUtils
  and OCPP20ServiceUtils, with dispatcher in OCPPServiceOperations.ts

ChargingStation.ts no longer has any direct knowledge of OCPP version-
specific service classes. All version dispatch is handled by the ocpp/
component through factories and dispatchers.

Add unit tests for createOCPPServices (4 tests) and
buildBootNotificationRequest (6 tests) in existing test files.