Refactor cogs and update author formatting

Updated `__init__.py` to import specific cog classes
and added asynchronous `setup` functions for each.
Modified `info.json` to improve the formatting of the
"author" field for better readability.

modmail/__init__.py

@@ -1 +1,4 @@
-from .modmail import setup
+from .modmail import Modmail
+
+async def setup(bot):
+    await bot.add_cog(Modmail(bot))