Allow overriding pure text_input value during draw

[tarkah]

iced_native::widget::TextInput defines a draw method to override it's Value when drawn. This adds the same functionality to the pure version.

Difference here is caller must provide the Tree with associated state in it for the text input and it's up to them to make sure this is safe.

[hecrj]

Thanks! 🙇

Certainly necessary to implement some custom widgets with composition.