* Allow users of `TextInput` to know when a keypress had no effect
This PR makes the `TextInput` widget emit a `TextInputAction::KeyDownUnhandled`
action upon keypresses that don't actually make any change to the widget's selection.
This action is currently only emitted for the Up, Down, Left, and Right arrow keys,
but we can certainly add it to others like Backspace, Delete, etc if desired.
Use case: if you want to enable custom behavior when the user uses arrow keys
to navigate an empty TextInput widget, such as jumping up out of the TextInput focus
to edit the most recent message you just sent in a chat app, then this PR
is necessary. Otherwise there's no way to know whether a given input actually had
any effect on the TextInput's inner cursor/selection state.
* Add the FaceID usage description to iOS Info.plist
Allows Makepad apps to use biometric auth on iOS
* Allow saving/restoring the state of the `TextInput` widget
This redoes the changes introduced in #533, but modified for the new version of TextInput
* Properly restore the state of the TextInput
