Pytest (#162)

Port python tests to mscclpp.
Please run
`mpirun -tag-output -np 8 pytest ./python/test/test_mscclpp.py -x` to start pytest

---------

Co-authored-by: Saeed Maleki <saemal@microsoft.com>
Co-authored-by: Changho Hwang <changhohwang@microsoft.com>
Co-authored-by: Saeed Maleki <30272783+saeedmaleki@users.noreply.github.com>

python/test/fifo_test.cu

@@ -0,0 +1,12 @@
+// Copyright (c) Microsoft Corporation.
+// Licensed under the MIT license.
+
+#include <stdio.h>
+
+#include "mscclpp/fifo_device.hpp"
+
+extern "C" __global__ void __launch_bounds__(1024, 1) fifo(mscclpp::FifoDeviceHandle fifo) {
+  mscclpp::ProxyTrigger trigger;
+  trigger.fst = 123;
+  fifo.push(trigger);
+}