Automatically start wireplumber (no support for systemd services).

Index: src/daemon/pipewire.conf.in
--- src/daemon/pipewire.conf.in.orig
+++ src/daemon/pipewire.conf.in
@@ -360,6 +360,8 @@ context.exec = [
     #
     @sm_comment@{ path = "@session_manager_path@" args = "@session_manager_args@"
     @sm_comment@  condition = [ { exec.session-manager = !false } ] }
+    { path = "${LOCALBASE}/bin/wireplumber" args = ""
+      condition = [ { exec.session-manager = null } { exec.session-manager = true } ] }
     #
     # You can optionally start the pulseaudio-server here as well
     # but it is better to start it as a systemd service.
