Ivi shell remove input panel

input panel implementation puts contents of an application, which uses input_method protocol, on top of all other surfaces. It is not controllable with ivi-layout interface.

This is not acceptable for an In-Vehicle Infotainment platform. Because we have to ensure configured scenegraph cannot be hijacked by any rogue application.

Therefore, I am removing input panel implementation. If someone strongly opposes to remove it, I can make it configurable. But IMO it does not have any place in ivi-shell other than demo purposes.