Fixes for ImageView drawable visibility dispatch

Some apps rely on their drawables not getting not-visible hints via
setVisible when the window visibility changes. This manifests as
additional animations, such as crossfading from placeholders when the
window becomes visible again.

Apps should be able to handle this case in the future now that we have
more detailed reporting via onVisibilityAggregated, but to keep
existing apps working as-is, ImageView now operates in a compatibility
mode for targetSdkVersion < N and will only dispatch visibility
signals based on the same triggers used in M. New apps get the more
detailed signals.

Fix a bug where window visibility dispatch via onVisibilityAggregated
would double-dispatch "not visible" when the window is transitioning
from GONE => INVISIBLE or INVISIBLE => GONE.

Make the growing set of compatibility check fields in ImageView
static, matching the pattern from View.

Bug 30216207

Change-Id: I88875260bf6aaa23687c7d51353de8d633383531