Add new floating action menu for Accessibility targets. (4/n)

Patch action:
1. Drag and drop anywhere on the screen.
2. Stick on the closest left side or right side of the screen when dropping.
3. Apply the different styles.
 - Half oval style when dropping.
 - Oval style when dragging.

Bug: 173958541
Test: atest AccessibilityFloatingMenuTest
AccessibilityFloatingMenuViewTest AccessibilityTargetAdapterTest

Change-Id: I5f207b86b9ca4342f1414230c4d7524c59f48953