Remove CursorAnchorInfoRequest and related stuff

This CL removes CursorAnchorInfoRequest and related stuff
in favor of InputConnection.requestUpdateCursorAnchorInfo,
which is more easy to understand. This CL also deprecates
InputMethodManager#updateCursor and related stuff.

Rationale:
1. The spec of #updateCursor says that it provides the cursor
   position in local coordinates, while the input method
   requires it in the screen coordinates.
2. #updateCursor has never been enabled in AOSP, because
   InputMethodManager#isWatchingCursor always returned false.
3. There has been no way to let
   InputMethodManager#isWatchingCursor return true.
4. In L, InputMethodManager#updateCursorAnchorInfo is
   introduced to address all the issues above.

Given that we no longer need to support #updateCursor,
CursorAnchorInfoRequest is overkill when we need to convey
just a couple of parameters.

BUG: 17185263
BUG: 17182367

Change-Id: I4a577bfd02b37b9e56c80b8b41bb25afa95dd8ef