Fix the issue of committing text with newCursorPosition=0

Fix the issue that cusor is incorrectly positioned with the following
API:
  - commitText(text, 0)
  - setComposingText(text, 0)

Bug: 21476564
Bug: 240359838
Fix: 21476564
Test: atest FrameworksCoreTests:BaseInputConnectionTest

Change-Id: I537dc384deffaf74f38bbd158e0f433ca67fa047