[refactor]refactor attention kernel

Author: klhhhhh

fastvideo/attention/ring/kernels/__init__.py

@@ -35,6 +35,15 @@
     pytorch_attn_forward,
 )
 
+if HAS_FLASH_ATTN:
+    from flash_attn import flash_attn_func
+
+if HAS_SAGE_ATTENTION:
+    import sageattention
+
+if HAS_SPARSE_SAGE_ATTENTION:
+    from spas_sage_attn.autotune import SparseAttentionMeansim
+
 
 class AttnType(Enum):
     AITER = "aiter"