[V3 Everything] Package bot and write setup scripts (#964)

Ya'll are gonna hate me.

* Initial modifications

* Add initial setup.py

* working setup py help

* Modify setup file to package stuff

* Move a bunch of shit and fix imports

* Fix or skip tests

* Must add init files for find_packages to work

* Move main to scripts folder and rename

* Add shebangs

* Copy over translation files

* WORKING PIP INSTALL

* add dependency information

* Hardcoded version for now, will need to figure out a better way to do this

* OKAY ITS FINALLY FUCKING WORKING

* Add this guy

* Fix stuff

* Change readme to rst

* Remove double sentry opt in

* Oopsie

* Fix this thing

* Aaaand fix test

* Aaaand fix test

* Fix core cog importing and default cog install path

* Adjust readme

* change instance name from optional to required

* Ayyy let's do more dependency injection

redbot/cogs/downloader/converters.py

@@ -0,0 +1,24 @@
+import discord
+from discord.ext import commands
+from .repo_manager import RepoManager
+from .installable import Installable
+
+
+class RepoName(commands.Converter):
+    async def convert(self, ctx: commands.Context, arg: str) -> str:
+        return RepoManager.validate_and_normalize_repo_name(arg)
+
+
+class InstalledCog(commands.Converter):
+    async def convert(self, ctx: commands.Context, arg: str) -> Installable:
+        downloader = ctx.bot.get_cog("Downloader")
+        if downloader is None:
+            raise commands.CommandError("Downloader not loaded.")
+
+        cog = discord.utils.get(downloader.installed_cogs, name=arg)
+        if cog is None:
+            raise commands.BadArgument(
+                "That cog is not installed"
+            )
+
+        return cog