Several functions in FCC scorer not used/tested

As title. The functions below have zero reference counts.
```csharp
private static IDataScorerTransform Create(IHostEnvironment env, Arguments args, IDataView data, ISchemaBoundMapper mapper, RoleMappedSchema trainSchema)
{
Contracts.CheckValue(env, nameof(env));
env.CheckValue(data, nameof(data));
env.CheckValue(mapper, nameof(mapper));
if (args.Top< 0)
throw env.Except($"Number of top contribution must be non negative");
if (args.Bottom < 0)
throw env.Except($"Number of bottom contribution must be non negative");

var contributionMapper = mapper as RowMapper;
env.CheckParam(mapper != null, nameof(mapper), "Unexpected mapper");

var scorer = ScoreUtils.GetScorerComponent(env, contributionMapper);
var scoredPipe = scorer.CreateComponent(env, data, contributionMapper, trainSchema);
return scoredPipe;
}

// Factory method for SignatureBindableMapper.
private static ISchemaBindableMapper Create(IHostEnvironment env, Arguments args, IPredictor predictor)
{
Contracts.CheckValue(env, nameof(env));
env.CheckValue(predictor, nameof(predictor));
var pred = predictor as IFeatureContributionMapper;
env.CheckParam(pred != null, nameof(predictor), "Predictor doesn't support getting feature contributions");
return new BindableMapper(env, pred, args.Top, args.Bottom, args.Normalize, args.Stringify);
}

// Factory method for SignatureLoadModel.
private static ISchemaBindableMapper Create(IHostEnvironment env, ModelLoadContext ctx)
=> new BindableMapper(env, ctx);
```
I further commented out the whole `FeatureContributionCalculation.cs`, rebuilt my solution, and ran all tests starting with `FeatureCont`. Surprisingly, all tests passed.