ios, core: better notifications processing to avoid contention for database (#3485)

* core: forward notifications about message processing (for iOS notifications)

* simplexmq

* the option to keep database key, to allow re-opening the database

* export new init with keepKey and reopen DB api

* stop remote ctrl when suspending chat

* ios: close/re-open db on suspend/activate

* allow activating chat without restoring (for NSE)

* update NSE to suspend/activate (does not work)

* simplexmq

* suspend chat and close database when last notification in the process is processed

* stop reading notifications on message markers

* replace async stream with cancellable concurrent queue

* better synchronization of app and NSE

* remove outside of task

* remove unused var

* whitespace

* more debug logging, handle cancelled read after dequeue

* comments

* more comments

tests/MobileTests.hs

@@ -209,7 +209,7 @@ testChatApi :: FilePath -> IO ()
 testChatApi tmp = do
   let dbPrefix = tmp </> "1"
       f = chatStoreFile dbPrefix
-  Right st <- createChatStore f "myKey" MCYesUp
+  Right st <- createChatStore f "myKey" False MCYesUp
   Right _ <- withTransaction st $ \db -> runExceptT $ createUserRecord db (AgentUserId 1) aliceProfile {preferences = Nothing} True
   Right cc <- chatMigrateInit dbPrefix "myKey" "yesUp"
   Left (DBMErrorNotADatabase _) <- chatMigrateInit dbPrefix "" "yesUp"