[Kernel] Introduce sglang.kernels namespace and migrate scattered triton_ops kernels (RFC #29630, Phase 2) (#30044)

Co-authored-by: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

benchmark/kernels/decoding_attention_triton/triton_flashinfer_cudnn.py

@@ -6,8 +6,8 @@ import torch
 import torch.utils.benchmark as benchmark
 from flashinfer import BatchDecodeWithPagedKVCacheWrapper
 
+from sglang.kernels.ops.attention.decode_attention import decode_attention_fwd
 from sglang.srt.layers.attention.flashinfer_backend import should_use_tensor_core
-from sglang.srt.layers.attention.triton_ops.decode_attention import decode_attention_fwd
 
 
 def benchmark_forward(