kde integration: implement plasmoid to show notes

[Ri0n]

qmenu for notes on wayland works pretty bad (it's shown in the center of the screen)
As an alternative, it's possible to implement a Plasmoid.
Many native Plasma tray items have plasmoids on left click. It fits well to show notes

see https://develop.kde.org/docs/plasma/widget/
more examples are in /usr/share/plasma/plasmoids
those usually require C++ plugins at /usr/lib64/qt6/qml/org/kde/plasma/private
check for example plasma-pa sources.