Explore Adopting EditContext API

[hediet]

Missing functionality before this can be merged:

• Setting to toggle between NativeEditContext and old TextArea based implementation (defaults to old TextArea implementation)
• Screen-Reader support. I didn't figure out how to use the text area element for that, as editContext does not seem to work with it. So I guess we have to use the dom + dom selection. (basically the focused dom element has to have dom nodes that expose the text to the screen-reader, it also has to support text selection and update the selection so that screen-readers see what is selected. This dom node stays invisible though! Just for testing we can make it visible). We should definitely reach out to screen reader users to get feedback on this!
• Copy Paste Support
• Enter does not seem to work