Gets the guid with specific survey id and version and uses that to retrieve a schema. Latest version schema will be retrieved if version is omitted

Parameters: survey_id (str): survey id of the schema metadata. version (str) (optional): version of the survey. schema_firebase_repository (SchemaFirebaseRepository): injected dependency for interacting with the schema collection in firestore. schema_processor_service (SchemaProcessorService): injected dependency for interacting with the schema collection in firestore.