SPFresh implementation based on SPTAG (#405)

[MaggieQi]

• Initial commit

• init from update version

• merged code

• backup

• continue

• update the initial work version

• fix ExtraDynamicSearcher

• fix vectorTranslateMap

• fix compiling issues

• fix compling

• fix compiling

• add merge

• add merge re-assign

• TODO: add steady state test

• init steady state test

• Init SPDKIO

• optimize split

• fix align_round

• modify steady state: delete after search

• modify trace

• need to figure out disk usage

• modify steadystate

• need to debug load index

• fix delete by metadata

• add spfresh exe

• finish benchmark

• steady state complete

• add KVTest

• fix compiling errors

• Init SPDKIO

• optimize split

• add KVTest

• fix compiling errors

• change update vector to partital read

• modify merge

• fix build

• mem impl

• fix correctness

• Refactor code

• add spdk as module

• add isal-l_crypto as submodule

• initial spdk integration

• build queue infra

• spdk working

• add reference bdev.json

• static spfresh search done

• need to debug split

• debug for GC/ReAssign

• finish debug for GC/ReAssign

• Add build guide for SPDK version

• remove rocksdb

• add timeout support for SPDK

• modify code for timeout support

• fix timeout bug

• fix writeblocks segmentation fault

• fix bug: SPDK init fail

• fix timeout bugs

• batch ReadBlocks

• add batchSize option

• add timeout support for batched I/O

• Refine Index

• debug refine

• modify for stress test

• change update from metadata to mapping

• modify

• add IOStatistics for SPDK

• change ssd size

• modify for stress test

• fix ssd usage bug

• fix io limit

• modify ssd size for stress test

• for io stat

• modify for io

• fix for stress test

• temporarily remove rebuild

• fix BKT bug

• merge changes from Index.h BKTIndex.cpp and RelativeNeighborhoodGraph.h

• add lock for mapping

• fix merge bug

• Improve README.md

• add loading exclude head

• modify length

• fix code with AE repo

• add checkpoint & move rocksdb to thirdparty

• fix zstd dependency

• fix compiling

• fix running on SPDK

• enable rocksdb, need to debug update

• fix update

• add SPDK & Rocksdb checkpoint function

• pass test for checkpoint, todo: add persistentbuffer

• add wal logic

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