gpui: Set window title on Linux (#7589)

Release Notes:
- N/A


Hello everyone,
glad to be contributing to this awesome project! This just fixes a
simple todo!(linux) in gpui.

I also considered setting the window title in the hello world example,
let me know if I should add it in this PR as well.

Best Regards,
Christian Bergschneider

crates/gpui/src/platform/linux/window.rs

@@ -340,8 +340,15 @@ impl PlatformWindow for LinuxWindow {
     //todo!(linux)
     fn activate(&self) {}
 
-    //todo!(linux)
+    fn set_title(&mut self, title: &str) {
-    fn set_title(&mut self, title: &str) {}
+        self.0.xcb_connection.send_request(&x::ChangeProperty {
+            mode: x::PropMode::Replace,
+            window: self.0.x_window,
+            property: x::ATOM_WM_NAME,
+            r#type: x::ATOM_STRING,
+            data: title.as_bytes(),
+        });
+    }
 
     //todo!(linux)
     fn set_edited(&mut self, edited: bool) {}