### What this PR does / why we need it?
Overview: This pull request refactors speculative decoding for Eagle and
MTP proposers on Ascend hardware. It fixes a bug related to
draft_attn_metadatas being lost, migrates the lmhead feature, and adds
routing logic in MtpProposer.
Details:
1. Migrated the lmhead feature from mtp to eagle and normalized it in
eagle_proposer.
2. Fixed the bug where draft_attn_metadatas was lost after enabling
eagle mode in the merge graph.
3. Added the routing for pcp and disable padded drafter batch; in mtp
mode, if pcp and disable padded drafter batch are not enabled, the
normalized file eagle_proposer will be used.
RFC: https://github.com/vllm-project/vllm-ascend/issues/5467
### Does this PR introduce _any_ user-facing change?
No
### How was this patch tested?
ut and test
- vLLM version: v0.14.1
- vLLM main:
dc917cceb8
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Signed-off-by: lilinsiman <lilinsiman@gmail.com>
7932255c06