Auto-detect headers

[luisquintanilla]

System Information (please complete the following information):

• Model Builder Version: CLI 16.1.0

Training on a file without header because has-header flag default is true takes the first row as the column names. It would be good to have it default to false and autodetect/generate headers unless users explicitly say it had header.

Dataset:

Wow... Loved this place.    1
Crust is not good.  0
Not tasty and the texture was just nasty.   0

Command:

mlnet classification --name classification --dataset yelp_labelled.txt --label-col 1

ModelInput:

// This file was auto-generated by ML.NET Model Builder. 

using Microsoft.ML.Data;

namespace Classification.Model
{
    public class ModelInput
    {
        [ColumnName("Wow... Loved this place."), LoadColumn(0)]
        public string Wow____Loved_this_place_ { get; set; }

        [ColumnName("1"), LoadColumn(1)]
        public string _1 { get; set; }

    }
}

[JakeRadMSFT]

@justinormont @beccamc do we have anything that is good at guessing if there is a header?

[LittleLittleCloud]

Add a third option for has-header flag should be able to solve this