Use the system bus.

Added a dbus service file so we can own the
com.steampowered.SteamOSManager1 name.
Also added a systemd service file
Also add a dbus .conf file to allow any process to talk
to manager for now.

data/com.steampowered.SteamOSManager1.conf

@@ -0,0 +1,16 @@
+<?xml version="1.0" encoding="UTF-8"?>
+
+<!DOCTYPE busconfig PUBLIC
+ "-//freedesktop//DTD D-BUS Bus Configuration 1.0//EN"
+ "http://www.freedesktop.org/standards/dbus/1.0/busconfig.dtd">
+<busconfig>
+  <!-- Only root can own the service -->
+  <policy user="root">
+    <allow own="com.steampowered.SteamOSManager1"/>
+  </policy>
+
+  <!-- Anyone can send messages to the service -->
+  <policy context="default">
+    <allow send_destination="com.steampowered.SteamOSManager1"/>
+  </policy>
+</busconfig>

data/com.steampowered.SteamOSManager1.service

@@ -0,0 +1,5 @@
+[D-BUS Service]
+Name=com.steampowered.SteamOSManager1
+Exec=/usr/lib/steamos-manager
+User=root
+SystemdService=steamosmanager.service

data/steamosmanager.service

@@ -0,0 +1,7 @@
+[Unit]
+Description=SteamOS Manager Daemon
+
+[Service]
+Type=dbus
+BusName=com.steampowered.SteamOSManager1
+ExecStart=/usr/lib/steamos-manager

src/main.rs

@@ -35,7 +35,7 @@ async fn main() -> Result<()>
     
     let manager = manager::SMManager {};
 
-    let _system_connection = ConnectionBuilder::session()?
+    let _system_connection = ConnectionBuilder::system()?
     .name("com.steampowered.SteamOSManager1")?
     .serve_at("/com/steampowered/SteamOSManager1", manager)?
     .build()