lookandfeel: Remove inconsistency between InputPanel::active and Qt.inputMethod.visible

Virtual Keyboard (InputPanel) would follow the input method's status regardless of whether it visible on screen or not. In this case there was an additional property which introduced a desync between those states, and as a result virtual keyboard didn't show on a screen but still consumed arrows and Enter key for its internal key navigation just because input method "thinks" it is visible.

This patch removes the inconsistency, but the input panel would always show up on start (on X11). So at least user can see what "eats" their keys.