Add argument "fields" to the get_prices function

[rzhli]

If I am interested in specific column like low, and want only return that data, there should be an argument keyword like fileds allow me to achieve that.

It will be better if get_prices function add fields::Vector{String} like:

get_prices(symbol::String; range::String="5d", interval::String="1d", ..., divsplits::Bool=false, wait::Float64=0.0, fields::Vector{String})

where fields = ["Open", "High", "Low", "Close", "Adj Close"])

[eohne]

The get request always returns all of these fields so I don't think there is much to be gained from having a fields argument.

Put differently having a fields argument is practically the same as just getting the dictionary from get prices and then taking the relevant columns from there.