Add KUKSA.val databroker image features

Rework inclusion of KUKSA.val databroker server and client support
into image features that can be specified via IMAGE_FEATURES, and
use that in our demo image definitions.  As well, add a new
agl-kvm-host-kuksa feature that allows configuring the KVM demo
build to run the databroker on the host instead of in the IVI
guest.  Some further application configuration changes are
required for that to fully work, those will come in follow up
commits.

Bug-AGL: SPEC-5082

Change-Id: Ice931fe924c1bf49709999eeabcb998ee191fc80
Signed-off-by: Scott Murray <scott.murray@konsulko.com>
Reviewed-on: https://gerrit.automotivelinux.org/gerrit/c/AGL/meta-agl-demo/+/29699
ci-image-boot-test: Jenkins Job builder account
Reviewed-by: Jan-Simon Moeller <jsmoeller@linuxfoundation.org>
Tested-by: Jenkins Job builder account
ci-image-build: Jenkins Job builder account