RunCommandWidget: Add System Dark theme support
This adds System dark theme support for run command widget.
Dark theme turns on when:-
- Global dark theme is turned on(Possible on Some Android 9 devices as well) or battery saver is turned on, on Android 10 or later
- Battery saver is turned on, on all Android versions.
This does not change with the App theme preference set by the user in KDEConnect settings.
Screenshots on Android 10