[FR]: Hide tray icon (in KDE) when there are no new news

[adam-tj]

Brief description of the feature request

In KDE tray icons can be hidden when an app isn't "relevant". I think the app would benefit from hiding itself in the "Status and Notifications" area when there are no new news while the "Show when relevant" setting is enabled.

[martinrotter]

https://qt-project.atlassian.net/browse/QTBUG-143696

[martinrotter]

FOR ME:

https://github.com/rjfovo/qt-plugins/blob/438aeb23d88d93d37ab493b4752d6329db40e594/platformtheme/statusnotifier/statusnotifieritem.cpp#L13
https://github.com/0xd34df00d/leechcraft/blob/18d4c564c10766d2f5ffebb722b294dda66bdf82/src/util/gui/fancytrayiconimpl.h