Remove reliance on web3 instance for name_to_address_middleware

[fselmo]

When we have a v7 branch going, the sync ENS name-to-address middleware can be re-written as:

def name_to_address_middleware(
    make_request: Callable[[RPCEndpoint, Any], Any],
    w3: "Web3",
) -> Middleware:
    normalizers = [
        abi_ens_resolver(w3),
    ]
    middleware = construct_formatting_middleware(
        request_formatters=abi_request_formatters(normalizers, RPC_ABIS)
    )
    return middleware(make_request, w3)

Removing the need to pass in a web3 instance to default_middlewares() in manager.py. It can then be passed in just as the other default middlewares, as the method reference name_to_address_middleware, rather than the method instance name_to_address_middleware(w3).