Add new Usb.ACTION_USB_STATE sticky broadcast for monitoring USB connect state

This can be used instead of ACTION_USB_CONNECTED and ACTION_USB_DISCONNECTED
by clients that need to be informed of both USB connect and disconnect events

Change-Id: Ic26927af2e775c2694d18775f9d574c97b095dfd
Signed-off-by: Mike Lockwood <lockwood@android.com>