Room dialog (#905)

* support ToolIcon className and fix label padding

* factor some ExportDialog classes out to Modal

* initial RoomDialog prototype

* change label for another-session button

* remove unused css

* add color comments

* Move the collaboration button to the main menu, add support for mobile

* remove button for creating another session

* add locks

* Fix alignment issue

* Reorder button

* reuse current scene for collab session

* keep collaboration state on restore

Co-authored-by: Jed Fox <git@twopointzero.us>

src/components/ExportDialog.tsx

@@ -112,10 +112,10 @@ function ExportModal({
   }
 
   return (
-    <div className="ExportDialog__dialog" onKeyDown={handleKeyDown}>
+    <div onKeyDown={handleKeyDown}>
       <Island padding={4}>
         <button
-          className="ExportDialog__close"
+          className="Modal__close"
           onClick={onCloseRequest}
           aria-label={t("buttons.close")}
           ref={closeButton}