Implemnet methods to drag a icon to given Workspace cell

The CL implements public methods to drag an Icon from AllApps to a
given cell in the workspace.

Bug: 199120092
Test: Launcher3Tests:com.android.launcher3.ui.TaplTestsLauncher3#testDragAppIconToWorkspaceCell
Test: https://android-build.googleplex.com/builds/abtd/run/L89300000953052361
Test: https://android-build.googleplex.com/builds/abtd/run/L44500000953013792
Change-Id: Ife16d1f1b55b809763dd40f5afee6711049a4729