Make various updates and fixes: (#164)

- Add BF16 support for SM90 and SM100
- Refactor Python APIs
- Other fixes and code refactoring

tests/test_lazy_init.py

@@ -0,0 +1,15 @@
+import torch
+import torch.multiprocessing as mp
+import deep_gemm
+
+
+def main(local_rank: int):
+    torch.cuda.set_device(local_rank)
+
+
+if __name__ == '__main__':
+    procs = [mp.Process(target=main, args=(i, ), ) for i in range(8)]
+    for p in procs:
+        p.start()
+    for p in procs:
+        p.join()