fix(tooltip): Let go of a ToolTip in the service when it closes, however it closed - #25137

…platform#25137 after review

The unoplatform#24592 tooltip tests reset the window content in finally (ca34dc1).
The unoplatform#25137 tests follow e7496a8: compiled on every head and skipped on
native WinUI with PlatformCondition instead of #if HAS_UNO, popups closed
through the public VisualTreeHelper.GetOpenPopupsForXamlRoot, and a new
test for a tooltip whose opening is cancelled during the show delay.

The source side of e7496a8 is already on this branch: the ToolTip
close notification (3cfe072) and the service-side clears it carries
from unoplatform#25102 (800247f).

…at was subscribed (port)

Port of the latest unoplatform#24592 round (0994593, bd13144, 94e4f41,
d62ceb9 and b825e58 on top of ca34dc1):
- Closing unsubscribes from the elements that were subscribed on open,
  kept in _themeSource and _dataContextSource, instead of reading the
  anchor and the container again, which change when the tooltip is set
  on another element while it is open.
- AttachToPopup and DetachFromPopup carry the inherited DataContext only,
  so a DataContext set or bound on the tooltip itself is not copied into
  the layer the owner provides.
- Popup.Child parents the tooltip: the explicit SetParent calls and the
  guard around the assignment are gone.
- The tests from those commits, the [Bindable] view model they use, and
  the comments.

6.8 differences:
- The theme subscription is still behind UNO_HAS_ENHANCED_LIFECYCLE, and
  the DataContext forwarding has its own unconditional pair (47830b3),
  so _themeSource sits in the gated pair and _dataContextSource in the
  other.
- 6.8 has ReadInheritedValueOrDefaultValue on DependencyObjectStore only,
  so it is called through IDependencyObjectStoreProvider, as Control does.
- Dropping SetParent holds on 6.8 too: Popup.Child goes through the same
  OnChildChangedPartialNative, and PopupPanel.Children.Add and Remove set
  and clear the parent (UIElement.AddChild/RemoveChild on Skia and WASM,
  BindableView on Android).
- The tests live in Tests/Windows_UI_Xaml_Controls. The hover helpers keep
  GetAbsoluteBoundsRect: 7c16adc only fixes the WinAppSDK test build.

unoplatform#25137 (c43992e) carries no source change beyond the earlier port:
ToolTipService.cs already matches it.

…sed-6.8

fix: Release the current ToolTip when it closes (backport #25137, #26096)

…6.7/pr-26098

fix: Release the current ToolTip when it closes (backport #25137, #26096) (backport #26098)

Takes Uno's servicing/6.8 from 6951c2c up to 5254ace (42 pull
requests). Conflicts, by area:

IME and TextBox (unoplatform#25984, backport of unoplatform#25804; unoplatform#25952, backport of unoplatform#25619;
unoplatform#25976, backport of unoplatform#25818)
- Takes upstream's composition design (unoplatform#25804): the browser's input is
  the source of truth for the text, compositions included. This drops
  the composition parts of the unoplatform#24502 port (90746b8): its
  TypeScript composition handling, the StartIndex/TextChangePending
  event arguments, the IsReadOnly forwarding to the hidden input, and
  its Given_TextBox.BrowserSoftKeyboard tests.
- Keeps the non-IME browser fixes on top of it, in the form their
  master pull requests have on unoplatform#25804: Enter raised once per press and
  tracked by key code (unoplatform#25174, with Given_TextBox.BrowserEnterKey from
  master in place of the Enter tests that lived in the dropped file),
  the iOS refocus on tap (unoplatform#25185), pastes without text and isIOS from
  BrowserInputHelper.
- Moves the unoplatform#26005 MaxLength fixes onto unoplatform#25804's native input path, as
  master has them: a refused browser edit keeps the TextBox's selection,
  TextBoxView.UpdateTextFromNative reports whether the edit went in, and
  the IME keeps its range on the applied text (master be85699, which
  d226897 had ported onto the unoplatform#24502 IME). Adds that commit's browser
  and platform-applied IME tests.
- TextBox.pointers.skia.cs: upstream's file (unoplatform#25619 iOS touch editing,
  unoplatform#25818, unoplatform#25804), with the unoplatform#25126 port (the hold acts when it starts,
  a touch right-tap keeps the caret) in the form master's unoplatform#25126 branch
  has it on unoplatform#25619, including focusing before the iOS hold timer acts
  and its iOS not-focusable test.

Pointers (unoplatform#25976, backport of unoplatform#25818)
- Tapped and RightTapped are raised once the PointerReleased bubbled
  (unoplatform#25818), with the unoplatform#25732 port's window coordinates (2-argument
  routed event args, RawPosition for ContextRequested), as master's
  unoplatform#25732 branch has them.
- The release wrapper of unoplatform#25818 keeps the unoplatform#25126 port's
  StopContextMenuTimer at the start of the release.

DependencyObject (unoplatform#26142, backport of unoplatform#26123)
- Takes upstream, then the code of unoplatform#25839 (97a2f17), which replaces
  this branch's unoplatform#25102 ports (800247f, be41da6, fd40bf9,
  7546379). DependencyObjectStore.Binder.cs, .alc.cs,
  Application.Alc.cs, ResourceDictionary.alc.cs and their tests now
  match unoplatform#25839; this drops 800247f's own
  SingleParentNonFE_Parent_Removes_Value_Then_Next_Parent_Starts_Clean
  test, which unoplatform#25839 doesn't have.

Imaging (unoplatform#25597, unoplatform#25915, unoplatform#25911, unoplatform#25897)
- Keeps this branch's side: it has the later forms of these fixes
  (unoplatform#25124, unoplatform#25559, unoplatform#25633 and unoplatform#26370 ports), where upstream has the
  6.8-only unoplatform#25597 design and earlier snapshots. Upstream's shared
  download, IgnoreImageCache and failed-load fixes are covered by
  SharedImageDecode. Adds upstream's When_Source_Outlives_Brushes test.

ToolTip (unoplatform#26098, backport of unoplatform#25137 and unoplatform#26096)
- Keeps this branch's unoplatform#25137 port and adds unoplatform#26096 in master's form: the
  service releases only a ToolTip it opened, and leaves one the app
  opened during the show delay to the app. Keeps both sides' tests.

Flyout (unoplatform#26062, backport of unoplatform#26060)
- This branch had the same commits already; keeps the "Keep
  non-resizable flyouts in window" port and its tests.

Also removes a helper pair in Given_AccessibleTextBox that both sides
added.