[iOS] wrong form data value when using autocomplete (playground demo included) #9486

Describe the bug
We got a lot of users complaining that they didn't receive the signup email. When checking their accounts we noticed that they often entered an email address like "infinfo@nstudio.io" or "jeff.jeff.bezos@amazon.com". We thought they were just mistyping their addresses, until we noticed that it had to do with autocompleting emails on ios.

To Reproduce

• on iOS (tested with iOS 14) start typing an email e.g. "jeff"
• now you see that "jeff.bezos@amazon.com" is suggested. click on the suggestion to use it
• the content of the Textfield is now "jeff.bezos@amazon.com"
• the content of the data model however is "jeffjeff.bezos@amazon.com" (what you typed before + the full autosuggestion)

Expected behavior
The data model should contain "jeff.bezos@amazon.com" instead of "jeffjeff.bezos@amazon.com"

Sample project
https://play.nativescript.org/?template=play-js&id=METmUA (Plain JS)
https://play.nativescript.org/?template=play-vue&id=eOi529 (VueJS)

Video preview
We're typing "et" and then using the autosuggested email "kundenzentrum@ethikbank.de". The data model then contains "etkundenzentrum@ethikbank.de"

Environment

• CLI: 8.0.2
• Cross-platform modules: 8.0.8
• Android Runtime: 8.0.0
• iOS Runtime: 8.0.0