[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/checks.py

@@ -0,0 +1,45 @@
+import asyncio
+
+import discord
+from discord.ext import commands
+
+__all__ = ["install_agreement", ]
+
+REPO_INSTALL_MSG = (
+    "You're about to add a 3rd party repository. The creator of Red"
+    " and its community have no responsibility for any potential "
+    "damage that the content of 3rd party repositories might cause."
+    "\n\nBy typing '**I agree**' you declare that you have read and"
+    " fully understand the above message. This message won't be "
+    "shown again until the next reboot.\n\nYou have **30** seconds"
+    " to reply to this message."
+)
+
+
+def install_agreement():
+    async def pred(ctx: commands.Context):
+        downloader = ctx.command.instance
+        if downloader is None:
+            return True
+        elif downloader.already_agreed:
+            return True
+        elif ctx.invoked_subcommand is None or \
+                isinstance(ctx.invoked_subcommand, commands.Group):
+            return True
+
+        def does_agree(msg: discord.Message):
+            return ctx.author == msg.author and \
+                   ctx.channel == msg.channel and \
+                   msg.content == "I agree"
+
+        await ctx.send(REPO_INSTALL_MSG)
+
+        try:
+            await ctx.bot.wait_for('message', check=does_agree, timeout=30)
+        except asyncio.TimeoutError:
+            await ctx.send("Your response has timed out, please try again.")
+            return False
+
+        downloader.already_agreed = True
+        return True
+    return commands.check(pred)