Refactor the design and improve the animations of Accessibility Floating Menu(1/n).

Goal: The goal of all following patches is to refactor the design to be compatible with the other system UI components. Also, support the feature “Drag to remove” and collision avoidance between other system windows based on the implementation. See more details: go/improvement_of_dragging_of_a11y_fab

Actions of this change:
1) Add the feature flag whether to apply the flag & spring animations into the menu.
2) Create the basic menu view related to accessibility features, and shown on the window.
3) Observe the settings content of the target features.

Bug: 227715451
Test: atest AccessibilityFloatingMenuControllerTest MenuViewLayerControllerTest MenuViewLayerTest
Change-Id: Ie9ee39c15ffceb1a967aeca2c80860d2411d85cb