[Core] Help Redesign (#2628)

* [Bot] Support new design

* [Context] use the new help in `ctx.send_help`

* [Commands] Update Cog and Group for help compat

- Removes a trap with all_commands, this isn't a good way to check this
- Adds a help property
- Fixes command parsing in invoke

* Redesigns red's help

* handle fuzzy help

* style

* handle a specific ugly hidden interaction

* fix bot-wide help grouping

* changelog

* remove no longer needed -

redbot/core/commands/context.py

@@ -62,10 +62,12 @@ class Context(commands.Context):
 
         return await super().send(content=content, **kwargs)
 
-    async def send_help(self) -> List[discord.Message]:
+    async def send_help(self, command=None):
         """ Send the command help message. """
-        command = self.invoked_subcommand or self.command
-        await super().send_help(command)
+        # This allows people to manually use this similarly
+        # to the upstream d.py version, while retaining our use.
+        command = command or self.command
+        await self.bot.send_help_for(self, command)
 
     async def tick(self) -> bool:
         """Add a tick reaction to the command message.