[Refactor][EAGLE] 7/N Merged PCP and disable_padded interface (#6811)

### What this PR does / why we need it?
[Refactor][EAGLE] 7/N Merged PCP and disable_padded interface into
eagle_proposer.py

This pull request significantly refactors the speculative decoding
mechanism by merging Parallel Context Processing (PCP) and Multi-Token
Prediction (MTP) functionalities directly into the eagle_proposer.py.
The changes aim to enhance the efficiency and correctness of distributed
speculative decoding, particularly by enabling the Eagle feature to work
seamlessly with the disable_padded interface. This involves detailed
adjustments to attention metadata, input/output processing, and state
management to ensure proper operation in parallel environments.

1. The PCP and MTP features are migrated to the eagle_proposer.py
2. The Eagle and PCP features are integrated
3. Enable the eagle feature to use the disable_padded interface

### Does this PR introduce _any_ user-facing change?
No

### How was this patch tested?
Tests and UT

- vLLM version: v0.15.0
- vLLM main:
83b47f67b1

---------

Signed-off-by: lilinsiman <lilinsiman@gmail.com>

vllm_ascend/attention/attention_v1.py

@@ -159,6 +159,7 @@ class AscendMetadata:
     num_decode_tokens: int = 0
     num_prefills: int = 0
     num_decodes: int = 0
+    num_decodes_flatten: int = 0
 
     # The sequence length per sequence. Sequence length means the computed
     # tokens + new tokens (is None if it is a decoding).

vllm_ascend/attention/context_parallel/attention_cp.py

@@ -117,6 +117,7 @@ class AscendAttentionCPMetadataBuilder(AscendAttentionMetadataBuilder):
 
         block_table = common_attn_metadata.block_table_tensor
         query_lens = query_start_loc_cpu[1:] - query_start_loc_cpu[:-1]
+        self.num_decodes_flatten = query_lens[:num_decodes].sum().item()
         seq_lens = common_attn_metadata.seq_lens_cpu[:num_reqs]
 
         long_seq_metadata = common_attn_metadata.prefill_context_parallel_metadata
@@ -146,7 +147,7 @@ class AscendAttentionCPMetadataBuilder(AscendAttentionMetadataBuilder):
             pcp_size = get_pcp_group().world_size
             if self.chunked_prefill_enabled and max_context_len_cpu > 0:
                 local_context_lens_allranks = (
-                    torch.tensor(num_computed_tokens_of_pcp_dcp)[num_decodes:num_reqs]
+                    torch.tensor(num_computed_tokens_of_pcp_dcp)[self.num_decodes_flatten :]
                     .to(self.device)
                     .to(dtype=torch.int32)
                 )
@@ -214,23 +215,24 @@ class AscendAttentionCPMetadataBuilder(AscendAttentionMetadataBuilder):
             prefill_metadata = AscendMetadataForPrefill(
                 pcp_metadata=pcp_metadata,
                 chunked_context=chunked_context_metadata,
-                block_tables=block_table[num_decodes:],
+                block_tables=block_table[self.num_decodes_flatten :, ...],
                 actual_seq_lengths_q=torch.cumsum(query_lens, dim=0),
             )
 
         if num_decodes > 0:
             num_computed_tokens_array = np.array(num_computed_tokens_of_pcp_dcp)
-            num_computed_tokens_array = num_computed_tokens_array[:num_decodes]
+            num_computed_tokens_array = num_computed_tokens_array[: self.num_decodes_flatten]
             # TODO: numpy array mode of the shared memory is used to improve performance
             decode_metadata = AscendMetadataForDecode(
                 num_computed_tokens_of_pcp_dcp=num_computed_tokens_array,
-                block_tables=block_table[:num_decodes],
+                block_tables=block_table[: self.num_decodes_flatten],
             )
 
         attn_metadata = AscendMetadata(
             num_actual_tokens=num_actual_tokens,
             num_decode_tokens=num_decode_tokens,
             num_actual_tokens_pcp_padded=num_actual_tokens_pcp_padded,
+            num_decodes_flatten=self.num_decodes_flatten,
             block_tables=block_table,
             query_start_loc=query_start_loc,
             seq_lens=seq_lens,
@@ -550,7 +552,7 @@ class AscendAttentionCPImpl(AscendAttentionBackendImpl):
             "actual_seq_lengths_kv": attn_metadata.decode_meta.num_computed_tokens_of_pcp_dcp[
                 :, self.pcp_rank, self.dcp_rank
             ],
-            "actual_seq_lengths": attn_metadata.actual_seq_lengths_q[: attn_metadata.num_decodes],
+            "actual_seq_lengths": torch.arange(attn_metadata.num_decodes_flatten) + 1,
         }
         graph_params = get_graph_params()
         forward_context: ForwardContext = get_forward_context()