Webassembly: Native Virtual keyboard support

Qt requires some form of virtual keyboard support on mobile. This can be accomplished either by using the Qt Virtual Keyboard module, or by integrating with the native virtual keyboard.

Application developers expect that the native virtual keyboard works, and a functional native virtual keyboard will also give the best user experience (compared to using Qt Virtual Keyboard)

Prioritised browsers are Safari on iOS and Chrome on Android.

Initially, there are two sub-tasks:

• Make sure the virtual keyboard pops up when a Qt text input gains focus. Web browsers will generally scroll/move the document to move the input element on screen and make room for the virtual keyboard, and this needs to work also for Qt apps.
• Handle key events / text-input events. On iOS, the existing key event handlers are sufficient for basic keyboard support. Android does not appear to send key events. Features like auto-complete, compositing, non-western language support, and emojis require handling text input events via Qts input method framework.