Allow multiple application windows

[jansav]

What would you like to be added: Allow user to start as many application windows they wants.

Why is this needed: There is no reason to limit amount of application windows. User might want to have separate windows for different clusters.

What is needed:

• [x] Figure out when kubeconfig synchronization should start & stop #5982
• [ ] Figure out when catalog synchronization should start & stop
• [x] Move starting and stopping check for updates to application start/stop #5981
• [ ] Figure out why lensProtocolRouterMain.rendererLoaded is needed and replace it with something more elegant
• [ ] Make sure that navigating from e.g. tray, application menu will work properly with multiple windows
  • [x] Replace hard-coded applicationWindow with createApplicationWindow() which is called once on application start. (applicationWindow -> getCurrentApplicationWindow) #5979
  • [ ] Introduce a way to detect which application window is "current"
• [x] Allow behavioural testing for multiple windows (remember that there can only be one document) #5979
• [ ] Add tray menu items for controlling application windows
• [ ] Add application menu items for controlling application windows

Original: https://github.com/lensapp/lens/issues/431

[arash-bizcover]

Allow user to start as many application windows she wants.

The user is not a she, he uses a male avatar. How rude are you