allow external USB host management

- Setting config_UsbDeviceConnectionHandling_component leads into
  launching specified Activity whenever USB device is connected.
- This allows external Activity to manage USB device based on
  its own setup and settings.
- Device access can be passed to other app with permission update
  by UsbManager.grantPermission.
- added UsbDeviceConnection.resetDevice() to reset USB device connected.
  This is necessary to get device out from AOAP.
- Test requires installing UsbHostExternalManagmentTestApp and
  AoapTestHost to USB host, and AoapTestDevice to USB Device.

bug: 26404209
Change-Id: I8e77ddc646c15454d9b2ecf1356924cf6351fc28