test/vsock: add big message test

This adds test for sending message, bigger than peer's buffer size.
For SOCK_SEQPACKET socket it must fail, as this type of socket has
message size limit.

Signed-off-by: Arseniy Krasnov <AVKrasnov@sberdevices.ru>
Reviewed-by: Stefano Garzarella <sgarzare@redhat.com>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>