Forbid some operations in asynchronous callbacks

Forbid some operations in asynchronous callbacks

In following cases cynara api operations regarding same cynara_async
structure called from within callbacks will return
CYNARA_API_OPERATION_NOT_ALLOWED:
- always within cynara_status_callback
- within cynara_response_callback called with
  CYNARA_CALL_CAUSE_SERVICE_NOT_AVAILABLE or CYNARA_CALL_CAUSE_FINISH
  cause.

It regards following api funtions:
- cynara_async_check_cache()
- cynara_async_create_request()
- cynara_async_process()
- cynara_async_cancel_request()

Change-Id: I1db22e0735e1905c4709c7f4c650cc8ca3f9b454