Move IInputMethod to com.android.internal.inputmethod

This CL Moves IInputMethod from

  com.android.internal.view

to

  com.android.internal.inputmethod

to be consistent with other IME-related internal files.

This is a mechanical refactoring of internal details.  There should be
no user/developer observable behavior change in this CL.

Bug: 234882948
Test: presubmit
Change-Id: I1a43c2ad1f932ecb9201b3958becb475fb2d718d