user_manager: Start bringing up user manager

src/user_manager.rs

@@ -0,0 +1,30 @@
+/*
+ * Copyright © 2023 Collabora Ltd.
+ * Copyright © 2024 Valve Software
+ * Copyright © 2024 Igalia S.L.
+ *
+ * SPDX-License-Identifier: MIT
+ */
+
+use anyhow::Result;
+use zbus::{interface, Connection};
+
+use crate::API_VERSION;
+
+pub struct SteamOSManagerUser {
+    connection: Connection,
+}
+
+impl SteamOSManagerUser {
+    pub async fn new(connection: Connection) -> Result<Self> {
+        Ok(SteamOSManagerUser { connection })
+    }
+}
+
+#[interface(name = "com.steampowered.SteamOSManager1.UserManager")]
+impl SteamOSManagerUser {
+    #[zbus(property(emits_changed_signal = "const"))]
+    async fn version(&self) -> u32 {
+        API_VERSION
+    }
+}