[Help] Detatch menu usage into a task (#2725)

* [Help] Detatch menu usage into a task

  - This resolves #2712
  - This is a minor API change. Conceptually, the difference is minor in
  nature `bot.send_help_for` returns when help has been sent, however
  this can now be prior to when the help menu (if one is in use) is
  closed.

  - This should not be considered breaking as there is and has been a
  a warning about this file's APIs being still up for unannounced modifications
  No developers should be currently relying on this behavior.

* operator precendence

redbot/core/commands/help.py

@@ -26,6 +26,7 @@
 # Additionally, this gives our users a bit more customization options including by
 # 3rd party cogs down the road.
 
+import asyncio
 from collections import namedtuple
 from typing import Union, List, AsyncIterator, Iterable, cast
 
@@ -555,10 +556,13 @@ class RedHelpFormatter:
                             )
                         )
         else:
-            if len(pages) > 1:
-                await menus.menu(ctx, pages, menus.DEFAULT_CONTROLS)
-            else:
-                await menus.menu(ctx, pages, {"\N{CROSS MARK}": menus.close_menu})
+            # Specifically ensuring the menu's message is sent prior to returning
+            m = await (ctx.send(embed=pages[0]) if embed else ctx.send(pages[0]))
+            c = menus.DEFAULT_CONTROLS if len(pages) > 1 else {"\N{CROSS MARK}": menus.close_menu}
+            # Allow other things to happen during menu timeout/interaction.
+            asyncio.create_task(menus.menu(ctx, pages, c, message=m))
+            # menu needs reactions added manually since we fed it a messsage
+            menus.start_adding_reactions(m, c.keys())
 
 
 @commands.command(name="help", hidden=True, i18n=T_)