A11y CTS fixes for Fugu.

Moving magnification center in test away from the center of the
screen, which is the default. When it exactly matches the default,
setCenter returns false, which is not what the test expects.

Moving global actions into their own InstrumentationTestCase. A
couple of these tests were causing flakiness on following tests when,
for example, the HOME intent got fired while the next test was
setting up the activity. Rather than try to deal with the timing
issues, moving the tests into a class that won't try to set up
activities at all.

Skipping test for window divider for Android TV, which doesn't
implement split-screen window mode.

Skipping gesture dispatch tests for devices without touch screens.

Also added some waits for idle to the soft keyboard test. I believe
it was counting windows before its activity was ready and getting
confused.

Bug: 28450244
Change-Id: Ie09e5808350eae85670c7e2a0764732c579b5dfb
5 files changed