add serializer methods (#7914)
Description: I have added two methods serializer and deserializer
methods. There was method called save local but it saves the to the
local disk. I wanted the vectorstore in the format using which i can
push it to the sql database's blob field. I have used this while i was
working on something
@rlancemartin, @eyurtsev
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Co-authored-by: Harrison Chase <hw.chase.17@gmail.com>
