[Server] update reademe, add conf file, updata test_cli

[ASR] Support editing num_decode_left_chunks in cli and server

[server][asr] do not reset result for web ws api

[Doc]update ds2 offline aishell librispeech,test=doc

[server][asr] support endpoint for conformer streaming model

[speechx] add nnet_decoder_chunk opt

[server] fix hifigan pad value

[server] update engine

[speechx] fix speech ws example

[speechx] fix speechx; rm simdjson

[speechx] refactor frontend

[ASR] refactor ds2, cli, server with espent datapipeline