[Tracker] Alias and CustomCom Rewrite

> Customcom uses commands not attached to the bot object for something which should be a trivial response.
> Alias uses discord.py's stringview and a subclass of string.Formatter used for string formatting in a way which breaks some things which should be valid. (#2879)

These two cogs are very fragile and are full of bugs. Some examples include:

CC:
- No way to edit random ccs (#2301)
- No option to use everyone mentions (#2518)

Alias:
- Parameters following an aliased command have newlines stripped (#2704)
- f-strings and .format do not work in aliased commands (#2719)
- Aliases seem to take a long time to run (#2935)
- Smart quotes cause a hidden error (#3055)
- No way to add defaults to parameters (#2011)

The best way to fix all of these errors is to rewrite these cogs. A recommended implementation can be found in #3602.