Add hnsw and read file

apps/app.cpp

data/sift_groundtruth.ivecs

data/sift_query.fvecs

include/helper.h

include/hnsw.h

src/CMakeLists.txt

src/helper.cpp

src/hnsw.cpp

tests/CMakeLists.txt

tests/test_helper.cpp

tests/test_ipre.cpp

tests/test_matrix.cpp