Bump discord.py to 1.7.0 (#4928)

* Bump discord.py, but to the git version for now

* Import GuildConverter from d.py and deprecate our implementation

* Import PartialMessageConverter in our commands extension

* Use newly added `Cog.has_error_handler()` rather than private method

* Update snowflake regex to use 20 as max length

See Rapptz/discord.py#6501

* Use new supported way for custom cooldown buckets

* Include group args in command signature

* Update code to use `Client.close()` over `Client.logout()`

* Add StageChannelConverter and StoreChannelConverter

* Fix AttributeError in licenseinfo

redbot/core/commands/help.py

@@ -275,6 +275,20 @@ class RedHelpFormatter(HelpFormatterABC):
             "You can also type {ctx.clean_prefix}help <category> for more info on a category."
         ).format(ctx=ctx)
 
+    @staticmethod
+    def get_command_signature(ctx: Context, command: commands.Command) -> str:
+        parent = command.parent
+        entries = []
+        while parent is not None:
+            if not parent.signature or parent.invoke_without_command:
+                entries.append(parent.name)
+            else:
+                entries.append(parent.name + " " + parent.signature)
+            parent = parent.parent
+        parent_sig = (" ".join(reversed(entries)) + " ") if entries else ""
+
+        return f"{ctx.clean_prefix}{parent_sig}{command.name} {command.signature}"
+
     async def format_command_help(
         self, ctx: Context, obj: commands.Command, help_settings: HelpSettings
     ):
@@ -300,9 +314,9 @@ class RedHelpFormatter(HelpFormatterABC):
         description = command.description or ""
 
         tagline = (help_settings.tagline) or self.get_default_tagline(ctx)
-        signature = _(
-            "Syntax: {ctx.clean_prefix}{command.qualified_name} {command.signature}"
-        ).format(ctx=ctx, command=command)
+        signature = _("Syntax: {command_signature}").format(
+            command_signature=self.get_command_signature(ctx, command)
+        )
 
         aliases = command.aliases
         if help_settings.show_aliases and aliases: