agl-compositor-init-pipewire: Add a service for streaming PipeWire output

agl-compositor-init-pipewire: Add a service for streaming PipeWire output

This should be started after compositor starts to automatically stream
the pipewire output to the target.

We add it under agl-compositor-init-pipewire as they belong together.

Bug-AGL: SPEC-5234
Change-Id: I884c73e0d33045284224f439685a19990b1fcebc
Signed-off-by: Marius Vlad <marius.vlad@collabora.com>
Reviewed-on: https://gerrit.automotivelinux.org/gerrit/c/AGL/meta-agl/+/30638
Tested-by: Jan-Simon Moeller <jsmoeller@linuxfoundation.org>
Reviewed-by: Jan-Simon Moeller <jsmoeller@linuxfoundation.org>