feat<map> add ValuesByKeys for get values array in order [issue - 467]

[XiaKuan]

solve
#467

[XiaKuan]

This issue can also be resolved in this way

func main() {
    inputMap := map[string]int{"foo": 1, "bar": 2, "baz": 3}
    inputSlice := []string{"foo", "baz"}
    result := lo.Map(inputSlice, func(key string, _ int) int {
        return inputMap[key]
    })
}

But I think this is used more.
Is it recommended to add this API?

[shivamrazorpay]

Just a random doubt: If the key is not present in the map, then the order in the output slice will not be aligned to the input keys.
You can add that edge case in the example of Readme.
Your thoughts on it ??

[XiaKuan]

Thanks for your suggestion!
Another way would be to append nil or zero values to the slice,
This way, the order in the output slices is aligned with the input keys.
The focus of this method is on order information, and I think this is a better way to do it
WDYT?

[ccoVeille]

I agree with @shivamrazorpay

It's the first thing I thought about

I would expect to return an error in such case

[XiaKuan]

That seems reasonable.

I have resubmitted the code

[shivamrazorpay]

Hi, can you review it @samber ?

[ccoVeille]

LGTM 👍