Add wireplumber-config-agl bbappend

Add wireplumber-config-agl bbappend

This policy will change the default video source device to a
USB based camera device, such that camera-gstreamer (with default pipewiresrc)
would use the USB camera device to grab video frames.

Bug-AGL: SPEC-5024
Change-Id: I8dc124e1855de21e00dede6ff99f8b148f80b6dc
Signed-off-by: Marius Vlad <marius.vlad@collabora.com>
Reviewed-on: https://gerrit.automotivelinux.org/gerrit/c/AGL/meta-agl-demo/+/29599
ci-image-build: Jenkins Job builder account
Reviewed-by: Jan-Simon Moeller <jsmoeller@linuxfoundation.org>
Tested-by: Jenkins Job builder account
ci-image-boot-test: Jenkins Job builder account