Consistency in feature/label/weight/group names in LearnerInputBase classes

[Ivanidzo4ka]

We have this class which is base class for all(almost except KMeans) Trainers.Options

machinelearning/src/Microsoft.ML.Data/EntryPoints/InputBase.cs

Line 42 in d4f2dcf

public abstract class LearnerInputBase

In trainer catalog we use following names:

/// <param name="labelColumnName">The name of the label column.</param>
/// <param name="featureColumnName">The name of the feature column.</param>
/// <param name="rowGroupColumnName">The name of the group column.</param>
/// <param name="exampleWeightColumnName">The name of the example weight column (optional).</param>

It doesn't feel right to have this names in catalog and have other names in options class.
So we should make them consistent and update LearnerInputBase class to ones we use in catalog.