Jumping animation on MacosScaffold Toolbar when toggling Sidebar

[Jannik-Hm]

Description

When using the ToolBar in a MacosScaffold, on Sidebar toggle, the toolbar jumps around. This is a result of the animation being performed by MacosWindow on the entire MacosScaffold.

Steps To Reproduce

1. Execute a macos_ui app
2. toggle sidebar

Expected behavior

This animation should be happening without weird jumping artifacts.

For a proper solution the animation of the toolbar would need to be decoupled from the content area animation in the main window as it is currently in line 378 ff. in layout/window.dart.

Any ideas?