feat: integrate sampling kernels into sgl-kernel (#3086)

Co-authored-by: Zihao Ye <expye@outlook.com>

sgl-kernel/src/sgl-kernel/ops/utils.py

@@ -17,3 +17,10 @@ def _get_cache_buf(name: str, bytes: int, device: torch.device) -> torch.Tensor:
         buf = torch.empty(bytes, dtype=torch.uint8, device=device)
         _cache_buf[key] = buf
     return buf
+
+
+def _to_tensor_scalar_tuple(x):
+    if isinstance(x, torch.Tensor):
+        return (x, 0)
+    else:
+        return (None, x)