fix(widgets): dismiss open RawTooltip on Escape key (WCAG 1.4.13) - #192966

….13) (flutter#193183)

Reverts: [fix(widgets): dismiss open RawTooltip on Escape key (WCAG
1.4.13)](flutter#192966)

Initiated by: @b-luk

Reason for reverting: Breaks `Windows
framework_tests_widgets_leak_tracking`.
https://logs.chromium.org/logs/flutter/buildbucket/cr-buildbucket/8669930694849114497/+/u/run_test.dart_for_framework_tests_shard_and_subshard_widgets/stdout

```
01:23 +4311 ~114 -1: C:/b/s/w/ir/x/w/flutter/packages/flutter/test/widgets/raw_tooltip_test.dart: (tearDownAll) [E]
  Expected: leak free
    Actual: <Instance of 'Leaks'>
     Which: contains leaks:
            # The text is generated by leak_tracker.
            # For leak troubleshooting tips open:
            # https://github.com/flutter/flutter/blob/main/docs/contributing/testing/Leak-tracking.md
            notDisposed:
              total: 2
              objects:
                ValueNotifier<_OverlayEntryWidgetState?>:
                  test: Escape key dismisses hovered RawTooltip even when primaryFocus is on a sibling consuming Escape
                  identityHashCode: 520722467
                OverlayEntry:
                  test: Escape key dismisses hovered RawTooltip even when primaryFocus is on a sibling consuming Escape
                  identityHashCode: 418743465
            
            
  
  package:matcher                                              expect
  package:leak_tracker_testing/src/leak_testing.dart 69:24     LeakTesting.collectedLeaksReporter.<fn>
  package:leak_tracker_flutter_testing/src/testing.dart 74:37  maybeTearDownLeakTrackingForAll
  ===== asynchronous gap ===========================
  dart:async                                                   Zone.registerBinaryCallback
  package:flutter_test/src/test_compat.dart 302:3              _tearDownForTestFile
```

Original PR Author: @kevmoo

Reviewed By: @navaronbracke

The original PR description is provided below:

## Description

Improves `RawTooltip` keyboard accessibility (`WCAG 1.4.13 Dismissible`,
http://b/463905826):

- **`RawTooltip` `Escape` key dismissal**: Registers a
`HardwareKeyboard` handler in `RawTooltipState` that dismisses open
tooltips on `LogicalKeyboardKey.escape` (`KeyDownEvent`) and consumes
the key event when a tooltip is open, preventing `Escape` from
prematurely closing parent modal dialogs (such as `DatePickerDialog`)
while a tooltip is displayed.
- *(Note: The accompanying Material changes for `Autocomplete`,
`DrawerHeader`, and `TooltipThemeData.ignorePointer` will be submitted
separately to `packages/material_ui` in `flutter/packages` per
[flutter#188444](flutter#188444

Fixes http://b/463905826

## Pre-launch Checklist

- [x] I read the [Contributor Guide] and followed the process outlined
there for submitting PRs.
- [x] I read the [Tree Hygiene] wiki page, which explains my
responsibilities.
- [x] I read and followed the [Flutter Style Guide], including [Features
we expect every widget to implement].
- [x] I signed the [CLA].
- [x] I listed at least one issue that this PR fixes in the description
above.
- [x] I updated/added relevant documentation (doc comments with `///`).
- [x] I added new tests to check the change I am making, or this PR is
[test-exempt].
- [x] I followed the [breaking change policy] and added [Data Driven
Fixes] where supported.
- [x] All existing and new tests are passing.

….13)" (flutter#193192)

Relands flutter#192966 (reverted in
flutter#193183) with `OverlayEntry`
disposal in `raw_tooltip_test.dart` and `FocusManager` early key-event
interception in `raw_tooltip.dart`.

### What changed since flutter#192966 (`f8c85519a060`)

1. **Test `OverlayEntry` Leak Fix (`raw_tooltip_test.dart`)**:
- In `raw_tooltip_test.dart` (`Escape key dismisses hovered RawTooltip
even when primaryFocus is on a sibling consuming Escape`), `flutter#192966`
passed an inline `OverlayEntry(...)` to `Overlay(initialEntries:
<OverlayEntry>[...])` without calling `entry.remove()` and
`entry.dispose()` in `addTearDown`. Because `Overlay` does not dispose
`initialEntries` on unmount, the `OverlayEntry`'s internal
`ValueNotifier<_OverlayEntryWidgetState?>` was flagged as `notDisposed`
by `leak_tracker` in CI (`Linux framework_tests_widgets_leak_tracking`).
- This reland captures `OverlayEntry? entry` and registers
`addTearDown(() { entry?.remove(); entry?.dispose(); })`. Verified
locally with `flutter test --dart-define=LEAK_TRACKING=true
test/widgets/raw_tooltip_test.dart`.
2. **Stop `Escape` Propagation Before Focus-Tree Shortcuts
(`raw_tooltip.dart`)**:
- In `flutter#192966`, `RawTooltipState` registered
`HardwareKeyboard.instance.addHandler(_handleKeyEvent)` alone. Because
`KeyEventManager` runs `HardwareKeyboard` handlers *before*
`FocusManager.handleKeyMessage` without stopping the focus-tree walk
when returning `true`, emptying `RawTooltip._openedTooltips` in
`HardwareKeyboard` caused `Escape` to still reach focused siblings
(`siblingReceivedEscape`) or `WidgetsApp`'s `Shortcuts` (`DismissIntent`
on enclosing `ModalRoute`s such as `DatePickerDialog`).
- This reland registers a single static pair
(`FocusManager.instance.addEarlyKeyEventHandler(_handleEarlyKeyEvent)`
plus `HardwareKeyboard.instance.addHandler(_handleHardwareKeyEvent)`
fallback when `primaryFocus == null`) when `RawTooltip._openedTooltips`
transitions from empty to non-empty, and removes them when the last open
tooltip closes or disposes. Returning `KeyEventResult.handled` from
`_handleEarlyKeyEvent` stops `FocusManager` before walking the focus
tree, and a second test (`Escape key dismisses open RawTooltip inside
WidgetsApp without invoking ancestor DismissIntent`) verifies both
cases.

### Original description

Fixes http://b/463905826

WCAG 1.4.13 (Content on Hover or Focus) requires a mechanism to dismiss
additional content triggered by pointer hover or keyboard focus
(`Escape` key) without moving pointer hover or keyboard focus, and
without unintended side effects such as dismissing an enclosing modal
dialog (`DatePickerDialog`) when a tooltip is open.

## Pre-launch Checklist

- [x] I read the [Contributor Guide] and followed the process outlined
there for submitting PRs.
- [x] I read the [Tree Hygiene] wiki page, which explains my
responsibilities.
- [x] I read and followed the [Flutter Style Guide], including [Features
we expect every widget to implement].
- [x] I signed the [CLA].
- [x] I listed at least one issue that this PR fixes in the description
above.
- [x] I updated/added relevant documentation (doc comments with `///`).
- [x] I added new tests to check the change I am making, or this PR is
[test-exempt].
- [x] All existing and new tests are passing.