fix: mobile UI and other fixes (#10177)

* remove legacy openMenu=shape state and unused actions

* close menus/popups in applicable cases when opening a different one

* split ui z-indexes to account prefer different overlap

* make top canvas area clickable on mobile

* make mobile main menu closable by clicking outside and reduce width

* offset picker popups from viewport border on mobile

* reduce items gap in mobile main menu

* show top picks for canvas bg colors in all ui modes

* fix menu separator visibility on mobile

* fix command palette items not being filtered

packages/excalidraw/tests/__snapshots__/excalidraw.test.tsx.snap

@@ -414,7 +414,7 @@ exports[`<Excalidraw/> > Test UIOptions prop > Test canvasActions > should rende
       </div>
     </button>
     <div
-      style="height: 1px; margin: .5rem 0px;"
+      style="height: 1px; margin: .5rem 0px; flex: 0 0 auto;"
     />
     <div
       class="dropdown-menu-group "
@@ -558,7 +558,7 @@ exports[`<Excalidraw/> > Test UIOptions prop > Test canvasActions > should rende
       </a>
     </div>
     <div
-      style="height: 1px; margin: .5rem 0px;"
+      style="height: 1px; margin: .5rem 0px; flex: 0 0 auto;"
     />
     <button
       aria-label="Dark mode"