Add MaxModelToExplore exit strategy to AutoMLExperiment.

[LittleLittleCloud]

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This PR adds the following API

AutoMLExperiment.SetMaxModelToExplore(int maxModel);

To AutoMLExperiment, which cancels AutoML training once after maxModel has reached.

This is useful for image classification and text classification in model builder, where no sweeping search space is expected.

This api can also combined with expeirment.SetTrainingTimeInSecond to form up a customized exit strategy.

@luisquintanilla for notification

[codecov]

Codecov Report

Merging #6402 (3dac528) into main (66b362a) will decrease coverage by 0.02%.
The diff coverage is 95.65%.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #6402      +/-   ##
==========================================
- Coverage   68.51%   68.48%   -0.03%     
==========================================
  Files        1167     1170       +3     
  Lines      246617   246950     +333     
  Branches    25764    25790      +26     
==========================================
+ Hits       168979   169135     +156     
- Misses      70923    71071     +148     
- Partials     6715     6744      +29     

Flag	Coverage Δ
Debug	68.48% <95.65%> (-0.03%)	⬇️
production	62.87% <ø> (-0.06%)	⬇️
test	88.95% <95.65%> (+0.02%)	⬆️

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Impacted Files	Coverage Δ
...rosoft.ML.AutoML.Tests/StopTrainingManagerTests.cs	94.11% <94.11%> (ø)
...Microsoft.ML.AutoML.Tests/AutoMLExperimentTests.cs	96.41% <100.00%> (+0.18%)	⬆️
src/Microsoft.ML.TorchSharp/Utils/FileUtils.cs	0.00% <0.00%> (-24.62%)	⬇️
...osoft.ML.KMeansClustering/KMeansPlusPlusTrainer.cs	83.92% <0.00%> (-7.16%)	⬇️
src/Microsoft.ML.FastTree/Training/StepSearch.cs	57.42% <0.00%> (-4.96%)	⬇️
src/Microsoft.ML.Data/Training/TrainerUtils.cs	66.26% <0.00%> (-3.82%)	⬇️
...crosoft.ML.StandardTrainers/Standard/SdcaBinary.cs	85.40% <0.00%> (-3.42%)	⬇️
...rc/Microsoft.ML.Tokenizers/Model/EnglishRoberta.cs	78.53% <0.00%> (-2.51%)	⬇️
src/Microsoft.ML.Sweeper/AsyncSweeper.cs	71.42% <0.00%> (-1.37%)	⬇️
...soft.ML.Transforms/Text/WordEmbeddingsExtractor.cs	85.74% <0.00%> (-1.14%)	⬇️
... and 18 more