Support asynchronous requests (accept `aiohttp.ClientSession` in `berserk.Client`?)

[jacksonthall22]

I'm writing a discord bot in PyCord, where the docs suggest performing all requests asynchronously. To be able to use berserk for my bot I would love if something like this worked out of the box:

async with aiohttp.ClientSession() as session:
    client = berserk.Client(session=session)
    ...  # Make api calls etc.