Updated BlobServiceClient to accept service-to-service token requests. This means HTTP services that rely on this Blob client, can accept service-to-service token and pass it through to Blob Service.
In short, previously:
- client -[CSAT]-> backup -[S2SToken]-> blob was possible
- identity -[S2SToken]-> backup -[S2SToken]-> blob wasn't possible
This diff makes the latter possible too, by overriding the accepts_services_token() for BlobServiceClient.