Clients which wish to enable the "atlasproxy" serialization protocol (expect tenant prefixes in namespaces, and return prefixed namespaces) will be required to pass a new mongodb/expectPrefix property in the body of their security token.

This ticket covers two related, but distinct pieces of work:

• Support a new property mongodb/expectPrefix in security tokens
• Upon receipt of a security token that contains "mongodb/expectPrefix": true, mark the connection where this token was received as being in "protcol=atlasproxy" and ensure that once set, this value is never changed.