options: ServerBlessings is no longer an IPCStreamListenerOpt.
options: ServerBlessings is no longer an IPCStreamListenerOpt.

This change makes ServerBlessing only a ServerOpt since we are no
longer exposing the stream API.

MultiPart: 2/2
Change-Id: If01c5989c6129e67f6c832c74f97c1f8d8e7c432

vanadium/go.v23,vanadium/go.v23,vanadium/go.v23