In full screen mode the virtual keyboard replicates the contents of
the focused input field to full screen input field located on top
of keyboard.

This mode can be activated by VirtualKeyboardSettings.fullScreenMode.

[ChangeLog] Added full screen input mode for super wide screens.

Change-Id: Ib2650c04767fb0945cc2bedc5b1801d254a15a41
Reviewed-by: Mitch Curtis <mitch.curtis@qt.io>