add kgn algorithm (#506) #600

Job	Run time
unit-tests	1s
annoy (random-xs-20-angular)	27s
balltree (random-xs-20-angular)	24s
bruteforce (random-xs-20-angular)	25s
ckdtree (random-xs-20-angular)	24s
descartes (random-xs-20-angular)	25s
diskann (random-xs-20-angular)	23s
dolphinnpy (random-xs-20-angular)	27s
elasticsearch (random-xs-20-angular)	26s
elastiknn (random-xs-20-angular)	24s
faiss (random-xs-20-angular)	25s
flann (random-xs-20-angular)	23s
glass (random-xs-20-angular)	23s
hnswlib (random-xs-20-angular)	23s
kdtree (random-xs-20-angular)	23s
kgn (random-xs-20-angular)	22s
luceneknn (random-xs-20-angular)	23s
milvus (random-xs-20-angular)	23s
mrpt (random-xs-20-angular)	24s
nndescent (random-xs-20-angular)	22s
n2 (random-xs-20-angular)	22s
nmslib (random-xs-20-angular)	24s
onng_ngt (random-xs-20-angular)	22s
opensearchknn (random-xs-20-angular)	24s
panng_ngt (random-xs-20-angular)	23s
pg_embedding (random-xs-20-angular)	20s
pgvector (random-xs-20-angular)	24s
pgvecto_rs (random-xs-20-angular)	24s
pynndescent (random-xs-20-angular)	22s
redisearch (random-xs-20-angular)	21s
qdrant (random-xs-20-angular)	22s
qg_ngt (random-xs-20-angular)	22s
qsg_ngt (random-xs-20-angular)	21s
scann (random-xs-20-angular)	21s
sptag (random-xs-20-angular)	21s
tinyknn (random-xs-20-angular)	22s
vald (random-xs-20-angular)	21s
vearch (random-xs-20-angular)	22s
vespa (random-xs-20-angular)	1s
voyager (random-xs-20-angular)	1s
weaviate (random-xs-20-angular)	1s
pynndescent (random-xs-16-hamming)	25s
datasketch (random-s-jaccard)	25s
pynndescent (random-s-jaccard)	24s
	15m 32s

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