Simplify state in SelectionModifierCursorController

This change removes some code from SelectionModifierCursorController
in favor of calling EditorTouchState instead.

Bug: 143852764
Test: Manual and unit tests
  atest FrameworksCoreTests:EditorTouchStateTest
  atest FrameworksCoreTests:EditorCursorDragTest
  atest FrameworksCoreTests:TextViewActivityTest
  atest FrameworksCoreTests:SuggestionsPopupWindowTest

Change-Id: I40f0ad8bd4eb0d4af33d0e2cd1a79c99812a9c40