feat: out-of-box experience (#2)

Reviewed-on: https://git.reya.su/reya/signed/pulls/2

crates/workspace/src/views/sidebar/import_dialog.rs

@@ -0,0 +1,11 @@
+use gpui::{App, Window, px};
+use gpui_component::WindowExt;
+
+/// Open the Import Identity dialog.
+///
+/// Currently a placeholder — the dialog only shows a title for now.
+pub fn open(window: &mut Window, cx: &mut App) {
+    window.open_dialog(cx, move |dialog, _window, _cx| {
+        dialog.title("Import identity").width(px(400.))
+    });
+}