Added testcase to EditTextTest

Due to changes made to TextView.java which will process KEYCODE_NUMPAD_ENTER
in the same manner as KEYCODE_ENTER, CTS test case is added to EditTextTest
to check that KEYCODE_NUMPAD_ENTER will be process just like KEYCODE_ENTER
and not insert space character as it used to.

This will take affect only in singleLine edittext.

Test: atest CtsWidgetTestCases
Bug: 141329038

Change-Id: I841855793b99c56f9fef4836825fc4c5c73c05e7