QT6 support maybe

[JarbasAl]

          we can do better here maybe...

• mycroft-gui sends a GuiID on connection, the proper fix would be to emit this to the correct gui bus instead
• the handler should LOG a legacy gui deprecation warning
• we can try to map this gui id to the clients singleton
• unfortunately GuiID is not sent in any follow up requests to the actual gui socket, only on the original message.... this should be fixed mycroft-gui side, this should likely be sent with every request as context from mycroft-gui side, but if a PR is accepted there then it should just fix the initial message / send the framework context properly, this hack is only needed assuming no PRs are accepted....
• when a gui connects, we can loop trough clients list, filter the clients without a platform, and if there is only one (as it should be most of the time) we can assign the framework received in legacy handler

Originally posted by @JarbasAl in #9 (comment)