Facilitating usage as a vector codec

[mdouze]

For some use cases, Faiss serves only as a storage engine for flat arrays of compressed vectors.
Maybe it would be useful to make a wrapper that makes this easier to use (especially to make compression transparent).
More details in this doc (visible internally in Meta):

https://docs.google.com/document/d/1v1KkD4KqrgHyjqgfykRQss37LdozZhqPMTYbymJlvDw/edit?usp=sharing

[alexanderguzhva]

@mdouze would it be possible to see this document? Thanks