Add preconfigured demo control panel images

Add preconfigured demo control panel images

Changes:
- Add kuksa-dbc-feeder configuration package for the gateway flavor
  of the control panel image.
- Split out the agl-demo-control-panel configuration into a separate
  package, and add alternative versions for running against the
  regular and gateway versions of the full demo.
- Add -preconfigured and -preconfigured-gateway flavors of the
  agl-ivi-demo-control-panel image that add the appropriate tweaks
  to support the full demo setups.

Bug-AGL: SPEC-5107, SPEC-5138

Change-Id: I290d08c0f7234f951b822b161bce8166fb62d346
Signed-off-by: Scott Murray <scott.murray@konsulko.com>
Reviewed-on: https://gerrit.automotivelinux.org/gerrit/c/AGL/meta-agl-demo/+/29943
Reviewed-by: Jan-Simon Moeller <jsmoeller@linuxfoundation.org>
Tested-by: Jan-Simon Moeller <jsmoeller@linuxfoundation.org>