Install battery applet, and make it work in the panel

applets/cosmic-applet-battery/src/upower_kbdbacklight.rs

@@ -0,0 +1,30 @@
+//! # DBus interface proxy for: `org.freedesktop.UPower.KbdBacklight`
+//!
+//! This code was generated by `zbus-xmlgen` `2.0.1` from DBus introspection data.
+//! Source: `Interface '/org/freedesktop/UPower/KbdBacklight' from service 'org.freedesktop.UPower' on system bus`.
+
+use zbus::dbus_proxy;
+
+#[dbus_proxy(
+    default_service = "org.freedesktop.UPower",
+    interface = "org.freedesktop.UPower.KbdBacklight",
+    default_path = "/org/freedesktop/UPower/KbdBacklight"
+)]
+trait KbdBacklight {
+    /// GetBrightness method
+    fn get_brightness(&self) -> zbus::Result<i32>;
+
+    /// GetMaxBrightness method
+    fn get_max_brightness(&self) -> zbus::Result<i32>;
+
+    /// SetBrightness method
+    fn set_brightness(&self, value: i32) -> zbus::Result<()>;
+
+    /// BrightnessChanged signal
+    #[dbus_proxy(signal)]
+    fn brightness_changed(&self, value: i32) -> zbus::Result<()>;
+
+    /// BrightnessChangedWithSource signal
+    #[dbus_proxy(signal)]
+    fn brightness_changed_with_source(&self, value: i32, source: &str) -> zbus::Result<()>;
+}