After this patch, there are three major text input widgets:

 * EditableText. This widget is a low-level editing control that
   interacts with the IME and displays a blinking cursor.

 * TextField. This widget is a Material Design text field, with all the
   bells and whistles. It is highly configurable and can be reduced down
   to a fairly simple control by setting its `decoration` property to
   null.

 * TextFormField. This widget is a FormField that wraps a TextField.

This patch also replaces the InputValue data model for these widgets
with a Listenable TextEditingController, which is much more flexible.

Fixes #7031

* Add cupertino to gallery and add CupertinoButto

* Use single quotes

* Add disabled state

* Some review notes

* Make button animation more responsive and tweak timing

* Renamed things Cupertino

* Button with background, move cupertino demos, move material demos

* Move 2 level list too

* Refactor various demo route names

* Some review notes

* More reviews and add test

* Linter as

* Move private constant up

This is apperently breaking some customers.

If this gets submitted, we should investigate why self-package imports
don't work for certain customers.

* Revert "Revert "Simplify path handling logic in dependency checker and devFS (#8414)" (#8467)"

This reverts commit 96ba7f76.

* Intentionally use a self-package URI in flutter_gallery

* tests to catch problems with self-package imports

This demo doesn't work properly in landscape and is confusing. It's
really more of a test of the material arc code.

Fixes #5710

Added a demo of BottomNavigation to the Gallery.

Turns out we have the same demo in the "Buttons" section now.
We don't need both.

* Pesto demo for the Flutter Gallery app.

* pesto.special.case

This demo burns battery continuously even when there's no change to the visual
appearance. This patch removes this demo to avoid giving the impression that
Flutter burns battery.

Related to #4120

* move the material_gallery/demos.dart script

* rename all_demos.dart to all.dart