Handle right and middle mouse button clicks

[swift-kim]

Contributes to https://github.com/flutter-tizen/flutter-tizen/issues/490.

• Specify FlutterPointerEvent.device_kind according to the actual device type.
• Handle multi device states correctly.
• Handle mouse hover events and right and middle click events correctly.
• Fix Evas_Event_Mouse_Down.button being incorrectly used as a device ID and use mouse_event->dev instead.
• Update kScrollOffsetMultiplier with the value used by Chromium/Linux GTK.

The code added to flutter_tizen_view.cc is mostly based on the Windows implementation (flutter_windows_view.cc).

To test right and middle clicks, you can use the GestureDetector widget (onSecondaryTapDown/onTertiaryTapDown).