In #42533, I disabled the up/down arrows for focus navigation in text fields, but we thought of a better way to do it, so this is that better way.

This change reverts the other change, and instead it tests the context of the node in the action to see if it's an EditableText node. If so, then it doesn't do the navigation action.

This disables the arrow key focus navigation for text fields. This was non-standard behavior for text fields, although it remains useful for other kinds of controls.

Fixes #42259

This attempts to reland #40186 and #41220, that were reverted in #41945.

The main modifications from the original PRs are that I predefine the shortcuts and actions maps instead of defining them inline in the build function, and I use a new mapEquals to do a deep comparison so that we don't rebuild modified things if the contents of the map haven't changed.

I also eliminated an operator== and hashCode that were defined on the Actions widget, since widgets shouldn't have those. (it's too bad though: I get an 85% speedup if we leave this in! Too bad it prevents rebuilding of the children...)

Fixes #40101

* add missing trailing commas

* add more missing trailing commas

* add more and more missing trailing commas

* Implement system fonts system channel listener

Previously, focus nodes created in the tab scaffold were not being disposed of properly, causing possible memory leaks. Also, the builder wasn't being passed the right context so that the FocusScope.of operator inside of a builder would find the focus scope for the given tab (it was being passed the context of the overall tab scaffold).

* CupertinoTabBar

* CupertinoButton

* update

* review

* WIP

* trying out different numbers

* apply intrinsic width and height

* update

* update behavior

* documentation

* wip

* fix tests

* constants

* respect theme

* respect theme

* add new test

* add new test

* update

* review

* update golden commit hash

* make CupertinoDynamicColor const constructible

* review

Add an autofocus parameter to widgets which use Focus widget internally, and update related docs.

This will allow developers to request that a particular widget be automatically focused when shown.

Fix a bug in CupertinoTextField where resizeToAvoidBottomInset didn't work.

Vibrate when starting scrollbar dragging.

(Breaking Change) Move some hardcoded pixel values to reusable constants.

Fix bug where selection menu appeared at top of screen for multiline inputs.