[Ozone/Wayland]Conditions for bubble to use platform widget

Add feature flag kOzoneBubblesUsePlatformWidgets. Change
requires_accelerated_widget to use_accelerated_widget_override
declared as optional<bool>:
  true: desktop native widget will always be used
  false: desktop native widget will never be used
  unspecified: depends on kOzoneBubblesUsePlatformWidgets feature and
    ozone platform capabilities.

Explicitly disable MultitaskNudgeWidget, it is a blinking widget around
maximize button and hints at MultitaskMenu feature. It reparents the
content_window of the bubble widget to manipulate its visibility from
the browser frame directly. disable this because it ambiguates which
frame_sink is producing contents to, and is not useful if it wants to
submit content as part of the browser frame.

Following tests are disabled:
  BrowserFrameTest.ChildWidgetsReceiveThemeUpdates
  HatsNextWebDialogBrowserTest.DialogResize
  HatsNextWebDialogBrowserTest.MaximumSize
  OmniboxPopupViewViewsTest.ClickOmnibox
  WebAppFrameToolbarBrowserTest_WindowControlsOverlay.DraggableRegionsIgnoredForOwnedWidgets
  OmniboxViewViewsTest.HandleExternalProtocolURLs

Bug: 1280332
Change-Id: Ia2dd7aca62b58e1c714fea22ae8764e3a13a6993
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/5370255


Reviewed-by: Dana Fried <dfried@chromium.org>
Reviewed-by: Xiyuan Xia <xiyuan@chromium.org>
Commit-Queue: Kramer Ge <fangzhoug@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1280474}