Add new floating action menu for Accessibility targets. (5/n)

Action:
AccessibilityFloatingMenu has two shape types, one is oval style, the other is half oval style.
- Half oval shape when dragging.
- Oval shape when dropping.
The patch will provide the capability of switch shape type by dragging into the screen edge or out.

Cherry picked from commit 0a2e8f9a

Bug: 173958541
Test: atest AccessibilityFloatingMenuTest
AccessibilityFloatingMenuViewTest AccessibilityTargetAdapterTest

Change-Id: Ib86713cd6a48e102cb9088beb6353391caeadc83
Merged-In: Ib86713cd6a48e102cb9088beb6353391caeadc83