[Eagle2]Fix multiple concurrent request crashes

[coolhok]

Motivation

fix some Eagle2 some bug

• hidden_states interference between multiple concurrent requests,in func (prepare_for_decode).
• Multiple concurrent occurrences have a certain probability of crashing.when req1 is finished,req2 is comming.in func (merge_batch).
• Multiple concurrent, add func filter_batch for handle AbortReq。

work with @jjjjohnson @bisunny

Need to rely on #2723

Modifications

• when Multiple concurrent in func prepare_for_decode,selected_input_index need add batch offset.
• when req1 is finished.req2 is new decode request.req1 hidden_states is none.
• add func filter_batch for handle AbortReq.

Checklist

• Format your code according to the Contributor Guide.
• Add unit tests as outlined in the Contributor Guide.
• Update documentation as needed, including docstrings or example tutorials.