Add assertNotEquals check to H602

There are some projects that mix assertNotEqual and assertNotEquals
in their testscripts. According to Python 3 source code, assertNotEquals
is also deprecated. This patch adds a check for assertNotEquals in H602 since
it already handles assertEquals and has not been released yet.

Lib/unittest/case.py:
    failIfEqual = assertNotEquals = _deprecate(assertNotEqual)

Change-Id: I087bd4b23cb2daa59a1df32926ddcc5cc2052f5c
Merge "Add assertNotEquals check to H602"