remove unused type restrict
add VoteOfMeMessage save test
add a flushAndWait test stub
import clean
fix flushAndWait impl
fix wrong assert
refactor UnsavedMessageQueue save method to sub-function,

fix unsaved queue timeout error path skip updating VoteTopicMessage bug
add stop function to help clean resources
use UnsavedMessageQueue.stop to help test exit clean sqlite connection
export stop function to EmbeddedHttpServer
more strict thread update VoteTopicMessage test