This adds the default shortcuts and actions for keyboard-based focus traversal of apps.

This list of shortcuts includes shortcuts for TAB, SHIFT TAB, RIGHT_ARROW, LEFT_ARROW, UP_ARROW, DOWN_ARROW, and the four DPAD keys for game controllers (because the DPAD produces arrow key events).

It doesn't yet include functionality for triggering a control (e.g. SPACE, ENTER, or controller buttons), because that involves restructuring some of the Flutter controls to trigger animations differently, and so will be done in another PR (#41220)

This re-lands #41417 with a slight change that will hopefully not tickle the analyzer as it did before. The last time I tried to land this, the analyzer succeeded for the analyze step in Cirrus, and locally, but failed in an integration test.

This reverts commit eb3e2f55 because of a suspected analyzer bug.  Reverting to investigate.

This addresses comments in the original PR (#41245) that introduced Intent.doNothing, adds tests, and fixes an issue with it.

This enables the manual tests to be built on a macOS desktop machine in desktop mode.

I created the macos directory by using flutter create --macos

* Add an 'unfocusable' focus node to allow developers to indicate when they don't want a Focus widget to be active

* more unfocusable changes. not working.

* Switch to focusable attribute

* Rename to canRequestFocus

* Turn off debug output

* Update docs

* Removed unused import

* more ui-as-code

* address review comments

Reland "Text inline widgets, TextSpan rework (#30069)" with improved backwards compatibility (#34051)

This reverts commit 14414f35.

This adds support for game controller buttons. It adds some supplemental USB HID codes that aren't available from the Chromium source code, and maps those on Android to the game pad buttons that Android supports. Other platforms are not supported yet.

This reverts commit 86862c1e.

* Merge in changes for inline widgets

* Make analyzer happy, fix tests

* Fix analyzer

* Add missing doc

* Docs on RichText

* Fix analyzer some more

* Remove whitespace at end of line

* Update goldens

* Text fixes

* Analyzer

This implements the keyboard shortcut handling and action invocation in order to provide a place in the infrastructure for keyboard events to trigger actions. This will allow binding of key events to actions like "move the focus to the next widget" and "activate button".

This adds support for an animated focusColor and hoverColor to InputDecorator. This color will blend with the background over a fade in period whenever the InputDecorator is focused or hovered, respectively.

It also adds a Listener to the TextField to listen for hover events.

This implements focus and hover handling for Material buttons. It inserts Focus widgets into the tree in order to allow buttons to be focusable via keyboard traversal (a.k.a. TAB traversal), and Listener widgets into the InkWell to allow the detection of hover states for widgets.

Addresses #11344, #1608, and #13264.

This re-lands the Focus changes in #30040. Correctness changes in routes.dart, and removes the automatic requesting of focus on reparent when there is no current focus, which caused undesirable selections.

Addresses #11344, #1608, #13264, and #1678
Fixes #30084
Fixes #26704

This reverts commit 4218c0bc.

Implements focus traversal for desktop platforms, including re-implementing the existing focus manager and focus tree.

This implements a Focus widget that can be put into a widget tree to allow input focus to be given to a particular part of a widget tree.

It incorporates with the existing FocusScope and FocusNode infrastructure, and has minimal breakage to the API, although FocusScope.reparentIfNeeded is removed, replaced by a call to FocusAttachment.reparent(), so this is a breaking change:

FocusScopeNodes must now be attached to the focus tree using FocusScopeNode.attach, which takes a context and an optional onKey callback, and returns a FocusAttachment that should be kept by the widget that hosts the FocusScopeNode. This is necessary because of the need to make sure that the focus tree reflects the widget hierarchy.

Callers that used to call FocusScope(context).reparentIfNeeded in their build method will call reparent  on a FocusAttachment instead, which they will obtain by calling FocusScopeNode.attach in their initState method. Widgets that own FocusNodes will need to call dispose on the focus node in their dispose method.

Addresses #11344, #1608, #13264, and #1678
Fixes #30084
Fixes #26704

* add trailing commas on list/map/parameters

* add trailing commas on Invocation with nb of arg>1

* add commas for widget containing widgets

* add trailing commas if instantiation contains trailing comma

* revert bad change

This makes Android raw key event handling use the "character" data coming from the engine properly, and gets rid of the "toLowerCase" hack that I was using to normalize logical key events, in favor of using the new "plainCodePoint" that has the unmodified code point (the code point as if no modifier keys were pressed).

This adds support for logical and physical key information inside of RawKeyEvent. This allows developers to differentiate keys in a platform-agnostic way. They are able to tell the physical location of a key (PhysicalKeyboardKey) and a logical meaning of the key (LogicalKeyboardKey), as well as get notified of the character generated by the keypress. All of which is useful for handling keyboard shortcuts.

This PR builds on the previous PR (#27620) which generated the key code mappings and definitions.

This adds some functions to the interface for RawKeyEventData and all subclasses that allow the recipient of an event to determine which modifier keys are currently being pressed without needing to know the specific modifier bitmasks for the platform.

Also adds constants for the modifier bitmasks for each platform, for completeness (and because I needed them anyhow to implement the above).

Added tests for the RawKeyEventData subclasses, and modified the raw_keyboard manual test app to show modifier keys being pressed. I also separated the different platform-specific subclasses into separate files.

Fixes #26155.

* Refactor of cupertino/material/widgets app

* update docs 

* Update tests for const

This reverts commit 61cf946b.

* Make CupertinoApp and MaterialApp both use WidgetsApp for Navigator

* Make CupertinoApp and MaterialApp const constructors

* Make WidgetsApp routes aware

* Update tests

* enable lint unnecessary_new

* fix tests

* fix tests

* fix tests

It was causing problems rolling Flutter into Fuchsia