When I was doing the MenuBar implementation, I made some changes to the PlatformMenuBar to allow it to understand shortcuts a little more, and to deprecate the body parameter rename it to child to match most other widgets.

These are those changes, separated out because they are separable, and I'm trying to make the MenuBar PR smaller.

Fixes #103965

* Use `curly_braces_in_flow_control_structures` for `packages/flutter_driver`

* Use `curly_braces_in_flow_control_structures` for `packages/flutter_goldens`

* Use `curly_braces_in_flow_control_structures` for `packages/flutter_goldens_client`

* Use `curly_braces_in_flow_control_structures` for `packages/flutter_localizations`

* Use `curly_braces_in_flow_control_structures` for `packages/flutter_test`

* Use `curly_braces_in_flow_control_structures` for `packages/flutter_web_plugins`

* fix comments

* Use `curly_braces_in_flow_control_structures` for `packages/integration_test`

* fix indentation

* Use `curly_braces_in_flow_control_structures` for `rendering`

* fix comments

* fix dangling

* Use `curly_braces_in_flow_control_structures` for `animation`

* Use `curly_braces_in_flow_control_structures` for `cupertino`

* fix comments

Use `curly_braces_in_flow_control_structures` for `foundation`, `gestures`, `painting`, `physics` (#104610)

* Use `curly_braces_in_flow_control_structures` for `foundation`

* Use `curly_braces_in_flow_control_structures` for `gestures`

* Use `curly_braces_in_flow_control_structures` for `painting`

* Use `curly_braces_in_flow_control_structures` for `physics`

* fix comments

* remove trailing space

* fix TODO style

This removes Shorcuts.of and Shortctus.maybeOf because they're not especially useful, since the only thing you can really set on a ShortcutManager is the shortcuts, and the Shortcuts widget that you give it to manages those, so if it rebuilds, it overwrites what you set.

Also, adds a Shortcuts.manager constructor and removes the manager argument to the Shortcuts widget.

Removing these will also eliminate an InheritedWidget for each Shortcuts widget, improving memory usage.

A bunch of random cleanup things I found while doing MenuBar development.

Changes an if test to an assert in binding.dart, since the if should always be true.
Adds the default ShortcutRegistrar that should have been in the ShortcutRegistry PR.
Moves a debug message in the FocusManager to print the result after the focus change instead of before.
Reorders the test parameters in theme_data_test.dart to match the order of the theme data fields everywhere else.

* Use `curly_braces_in_flow_control_structures` for `material`

* include test/material

* add back removed comments

* `Switch`: Add an interactive examples

* Update docs

* Update doc