FontEditor: Set Unicode ListView's focus proxy to its search box

Provides a visual cue that arrow key input is shared between these
widgets.

Userland/Applications/FontEditor/MainWidget.cpp

@@ -399,6 +399,7 @@ ErrorOr<void> MainWidget::create_models()
     m_unicode_block_listview->set_activates_on_selection(true);
     m_unicode_block_listview->horizontal_scrollbar().set_visible(false);
     m_unicode_block_listview->set_cursor(m_unicode_block_model->index(0, 0), GUI::AbstractView::SelectionUpdate::Set);
+    m_unicode_block_listview->set_focus_proxy(m_search_textbox);
 
     return {};
 }