fix: fix loading fonts cause assertion when remove or attach RenderObjects.

[andycall]

In Flutter 3.10, they had add checks for the fonts in loading stage when attach or detach RenderObjects on RenderObject tree.

We needs to delay the font loading to the end of frame to make sure renderObjects are not mutated at that times.

  @override
  void attach(PipelineOwner owner) {
    super.attach(owner);
    // If there's a pending callback that would imply this node was detached
    // between the idle phase and the next transientCallbacks phase. The tree
    // can not be mutated between those two phases so that should never happen.
    assert(!_hasPendingSystemFontsDidChangeCallBack);
    PaintingBinding.instance.systemFonts.addListener(_scheduleSystemFontsUpdate);
  }

  @override
  void detach() {
    assert(!_hasPendingSystemFontsDidChangeCallBack);
    PaintingBinding.instance.systemFonts.removeListener(_scheduleSystemFontsUpdate);
    super.detach();
  }