Add basic ContactsDataKind to ContactsTest (1/2)

* Use the same icons for the test app as the
  regular app so that custom QuickContacts
  actions have it.

* Make a copy of the fallback xml and add
  a ContactsDataKind to it

* Update the TestSyncAdapter to add
  the custom mimetype data row for null
  contacts that it sweeps up.

Test: Add null contacts, add test accounts, grant
  contacts permission to test account, toggle
  contacts sync for test account

Bug: 31549157

Change-Id: I59f0798c286e7043e0b40ca02f4336533534fae7