Maps: Add favorites panel with favorite places management

Userland/Applications/Maps/FavoritesPanel.gml

@@ -0,0 +1,28 @@
+@Maps::FavoritesPanel {
+    min_width: 100
+    preferred_width: 200
+    max_width: 350
+    layout: @GUI::VerticalBoxLayout {}
+
+    // Empty and favorites are toggled in visibility
+    @GUI::Frame {
+        name: "empty_container"
+        frame_style: "SunkenPanel"
+        layout: @GUI::VerticalBoxLayout {
+            margins: [4]
+        }
+
+        @GUI::Label {
+            text: "You don't have any favorite places"
+            text_alignment: "CenterLeft"
+        }
+    }
+
+    @GUI::ListView {
+        name: "favorites_list"
+        horizontal_padding: 6
+        vertical_padding: 4
+        should_hide_unnecessary_scrollbars: true
+        alternating_row_colors: false
+    }
+}