Support `bson(io::IO; kws...)`

[NeroBlackstone]

Is there a way to input serialized BSON into arbitrary IO like IOBuffer()?
Or is there a similar solution? please tell me thanks!

[NeroBlackstone]

I know, a workaround is convert kws... to Dict{Symbol, Any} by Dict(kws) and invoke bson(io::IO, doc::AbstractDict).

Do you think it makes sense to implement a function like bson(io::IO; kws...)? I can open a PR