gui: fix setting ChatWidgetContainerHandlerRepository in services

Signed-off-by: Rafał Malinowski <rafal.przemyslaw.malinowski@gmail.com>
gui: do not open chat windows for invalid chats

Signed-off-by: Rafał Malinowski <rafal.przemyslaw.malinowski@gmail.com>
gui: add UnreadMessagesCount property for ChatWidget

Signed-off-by: Rafał Malinowski <rafal.przemyslaw.malinowski@gmail.com>
gui: use unread messsages count property for notyfying in chatwindow

Signed-off-by: Rafał Malinowski <rafal.przemyslaw.malinowski@gmail.com>
single_window: use unread messsages count for notyfying in SingleWindow
tabs: use unread messsages count property for notyfying in tabs

Signed-off-by: Rafał Malinowski <rafal.przemyslaw.malinowski@gmail.com>