add functionality to close mqtt / realtime connection when needed
openRealtimeConnection(): Promise<boolean>
re-open realtime connection after closing itcloseRealtimeConnection(): Promise<boolean>
close realtime connection without affecting sync interval
On normal occurence, sync interval will be changed to 5 seconds from 30 seconds when realtime connection are closed
but ifcloseRealtimeConnection()are called, it will still on 30 seconds interval