LibGUI+Taskbar+Applets+Applications: Set various windows as Popups

Makes the Audio applet, Taskbar clock, CommandPalette, EmojiPicker,
and Assistant work as Popup windows. Popups are frameless, unmovable,
and unresizable by default, in addition to their preemptive function.
Also sets Assistant not to obey widget min size so its search result
area resizes correctly

Userland/Libraries/LibGUI/EmojiInputDialog.cpp

@@ -98,7 +98,8 @@ EmojiInputDialog::EmojiInputDialog(Window* parent_window)
     if (!main_widget.load_from_gml(emoji_input_dialog_gml))
         VERIFY_NOT_REACHED();
 
-    set_frameless(true);
+    set_window_type(GUI::WindowType::Popup);
+    set_window_mode(GUI::WindowMode::Modeless);
     set_blocks_emoji_input(true);
     resize(400, 300);