feat: cosmic settings daemon (#8)

* feat: cosmic settings daemon

* refactor: simplify by unifying trait for state and config

* chore: add ping and pong methods

* refactor: remove ping & pong methods

* cleanup

cosmic-settings-daemon/examples/simple.rs

@@ -0,0 +1,33 @@
+use futures::StreamExt;
+
+#[tokio::main]
+async fn main() -> zbus::Result<()> {
+	let connection = zbus::Connection::session().await?;
+
+	let proxy = cosmic_settings_daemon::CosmicSettingsDaemonProxy::new(&connection).await?;
+
+	println!("Display brightness: {}", proxy.display_brightness().await?);
+	println!(
+		"Keyboard brightness: {}",
+		proxy.keyboard_brightness().await?
+	);
+
+	let (config_path, name) = proxy
+		.watch_config("com.system76.CosmicTheme.Light", 1)
+		.await?;
+	dbg!(&config_path, &name);
+	let config_proxy = cosmic_settings_daemon::ConfigProxy::builder(&connection)
+		.path(config_path)?
+		.destination(name)?
+		.build()
+		.await?;
+	let mut stream = config_proxy.receive_changed().await?;
+
+	println!("Watching config for the libcosmic light theme...");
+	println!("Change the light theme in Settings > Appearance to trigger a signal.");
+	while let Some(c) = stream.next().await {
+		let c = c.args()?;
+		println!("Config changed: {} {}", c.id, c.key);
+	}
+	Ok(())
+}