Add source generator to generate search space class for all trainers/transformers

[LittleLittleCloud]

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#5993

This PR adds a source generator that generates SearchSpace classes for all estimators used in AutoML.Net and associated search space configurations which is in Json format.

The generated SearchSpace class looks like this (following is SearchSpace for LGBM)

using Microsoft.ML.SearchSpace;
using OptionAttribute = Microsoft.ML.SearchSpace.OptionAttribute;
using ColorsOrder = Microsoft.ML.Transforms.Image.ImagePixelExtractingEstimator.ColorsOrder;
using ColorBits = Microsoft.ML.Transforms.Image.ImagePixelExtractingEstimator.ColorBits;
using ResizingKind = Microsoft.ML.Transforms.Image.ImageResizingEstimator.ResizingKind;
using Anchor = Microsoft.ML.Transforms.Image.ImageResizingEstimator.Anchor;

#nullable enable

namespace Microsoft.ML.AutoML.CodeGen
{
    public class LgbmOption
    {
        [Range((int)4, (int)32768, init: (int)4, logBase: true)]
        [System.Diagnostics.CodeAnalysis.SuppressMessage("Declaration", "MSML_NoInstanceInitializers:No initializers on instance fields or properties")]
        public int NumberOfLeaves {get; set;} = 4;
        [Range((int)20, (int)1024, init: (int)20, logBase: true)]
        [System.Diagnostics.CodeAnalysis.SuppressMessage("Declaration", "MSML_NoInstanceInitializers:No initializers on instance fields or properties")]
        public int MinimumExampleCountPerLeaf {get; set;} = 20;
        [Range((double)2E-10, (double)1, init: (double)1, logBase: true)]
        [System.Diagnostics.CodeAnalysis.SuppressMessage("Declaration", "MSML_NoInstanceInitializers:No initializers on instance fields or properties")]
        public double LearningRate {get; set;} = 1;
        [Range((int)4, (int)32768, init: (int)4, logBase: true)]
        [System.Diagnostics.CodeAnalysis.SuppressMessage("Declaration", "MSML_NoInstanceInitializers:No initializers on instance fields or properties")]
        public int NumberOfTrees {get; set;} = 4;
        [Range((double)2E-10, (double)1, init: (double)1, logBase: true)]
        [System.Diagnostics.CodeAnalysis.SuppressMessage("Declaration", "MSML_NoInstanceInitializers:No initializers on instance fields or properties")]
        public double SubsampleFraction {get; set;} = 1;
        [Range((int)8, (int)1024, init: (int)256, logBase: true)]
        [System.Diagnostics.CodeAnalysis.SuppressMessage("Declaration", "MSML_NoInstanceInitializers:No initializers on instance fields or properties")]
        public int MaximumBinCountPerFeature {get; set;} = 256;
        [Range((double)2E-10, (double)1, init: (double)1, logBase: false)]
        [System.Diagnostics.CodeAnalysis.SuppressMessage("Declaration", "MSML_NoInstanceInitializers:No initializers on instance fields or properties")]
        public double FeatureFraction {get; set;} = 1;
        [Range((double)2E-10, (double)1, init: (double)2E-10, logBase: true)]
        [System.Diagnostics.CodeAnalysis.SuppressMessage("Declaration", "MSML_NoInstanceInitializers:No initializers on instance fields or properties")]
        public double L1Regularization {get; set;} = 2E-10;
        [Range((double)2E-10, (double)1, init: (double)1, logBase: true)]
        [System.Diagnostics.CodeAnalysis.SuppressMessage("Declaration", "MSML_NoInstanceInitializers:No initializers on instance fields or properties")]
        public double L2Regularization {get; set;} = 1;
        
        [System.Diagnostics.CodeAnalysis.SuppressMessage("Declaration", "MSML_NoInstanceInitializers:No initializers on instance fields or properties")]
        public string LabelColumnName {get; set;} = "Label";
        
        [System.Diagnostics.CodeAnalysis.SuppressMessage("Declaration", "MSML_NoInstanceInitializers:No initializers on instance fields or properties")]
        public string FeatureColumnName {get; set;} = "Feature";
        
        public string? ExampleWeightColumnName {get; set;}

    }
}

[codecov]

Codecov Report

Merging #6090 (b207cd2) into main (ea8ced0) will decrease coverage by 0.35%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##             main    #6090      +/-   ##
==========================================
- Coverage   68.63%   68.28%   -0.36%     
==========================================
  Files        1165     1089      -76     
  Lines      246498   241401    -5097     
  Branches    25703    25145     -558     
==========================================
- Hits       169188   164834    -4354     
+ Misses      70596    70019     -577     
+ Partials     6714     6548     -166     

Flag	Coverage Δ
Debug	68.28% <ø> (-0.36%)	⬇️
production	62.81% <ø> (-0.59%)	⬇️
test	88.74% <ø> (ø)

Flags with carried forward coverage won't be shown. Click here to find out more.

Impacted Files	Coverage Δ
...ML.Transforms/Text/StopWordsRemovingTransformer.cs	86.23% <0.00%> (-0.15%)	⬇️
src/Microsoft.ML.AutoML/API/ExperimentSettings.cs
....AutoML/ColumnInference/ColumnGroupingInference.cs
....AutoML/EstimatorExtensions/EstimatorExtensions.cs
...oft.ML.AutoML/Experiment/Runners/CrossValRunner.cs
...Microsoft.ML.AutoML/Experiment/SuggestedTrainer.cs
....ML.AutoML/PipelineSuggesters/PipelineSuggester.cs
...AutoML/TrainerExtensions/MultiTrainerExtensions.cs
...ML.AutoML/TransformInference/TransformInference.cs
...AutoML/TransformInference/TransformInferenceApi.cs
... and 68 more

[michaelgsharp]