Merge branch 'dev/unimplemented-placeholders' into 'development'

Sources/XXClient/Group/Functors/GroupGetCreatedMS.swift

Sources/XXClient/Group/Functors/GroupGetCreatedNano.swift

Sources/XXClient/Group/Functors/GroupGetId.swift

Sources/XXClient/Group/Functors/GroupGetInitMessage.swift

Sources/XXClient/Group/Functors/GroupGetName.swift

Sources/XXClient/Group/Functors/GroupGetTrackedId.swift

Sources/XXClient/Group/Functors/GroupSerialize.swift

Sources/XXClient/GroupChat/Functors/GroupChatNumGroups.swift

.../XXClient/UserDiscovery/Functors/UserDiscoveryGetId.swift

...MessengerClient/Messenger/Functors/MessengerConnect.swift

...XMessengerClient/Messenger/Functors/MessengerCreate.swift

...engerClient/Messenger/Functors/MessengerIsConnected.swift

...ssengerClient/Messenger/Functors/MessengerIsCreated.swift

...essengerClient/Messenger/Functors/MessengerIsLoaded.swift

...sengerClient/Messenger/Functors/MessengerIsLoggedIn.swift

...ngerClient/Messenger/Functors/MessengerIsRegistered.swift

.../XXMessengerClient/Messenger/Functors/MessengerLoad.swift

...XXMessengerClient/Messenger/Functors/MessengerLogIn.swift

...essengerClient/Messenger/Functors/MessengerRegister.swift

Sources/XXMessengerClient/Utils/MessengerFileManager.swift