A base interface for implementing QuiesceToken. A QuiesceToken is a unique key which is used in 2
main scenarios: 1. When requesting quiesce a token is generated and returned if the request was
approved. 2. When the system is QUIESCED a token is used by the permitted user (which requested
the quiesce) to execute space operations - only to the proxy with the correct token will be
allowed to perform those operations.