[1/N][Attention] Restructure attention: move files (#31916)

Signed-off-by: Matthew Bonanni <mbonanni@redhat.com>

vllm/model_executor/models/transformers/base.py

@@ -27,13 +27,14 @@ from torch import nn
 from transformers import AutoModel
 from transformers.modeling_utils import ALL_ATTENTION_FUNCTIONS
 
-from vllm.attention.backends.abstract import AttentionType
 from vllm.attention.layer import Attention
-from vllm.attention.layers.encoder_only_attention import EncoderOnlyAttention
 from vllm.config.utils import getattr_iter
 from vllm.distributed import get_pp_group, get_tp_group
 from vllm.distributed.utils import get_pp_indices
 from vllm.logger import init_logger
+from vllm.model_executor.layers.attention.encoder_only_attention import (
+    EncoderOnlyAttention,
+)
 from vllm.model_executor.layers.vocab_parallel_embedding import VocabParallelEmbedding
 from vllm.model_executor.models.interfaces import (
     SupportsEagle,
@@ -59,6 +60,7 @@ from vllm.model_executor.models.utils import (
     maybe_prefix,
 )
 from vllm.sequence import IntermediateTensors
+from vllm.v1.attention.backend import AttentionType
 
 if TYPE_CHECKING:
     from transformers import PreTrainedModel