amazon-sagemaker-examples [feat] Add TabTransformer and AutoGluon example notebooks as Amazon SageMaker algorithms

Added TabTransformer and AutoGluon example notebooks as Amazon SageMaker algorithms.
Modified existing JumpStart example notebooks LightGBM, CatBoost (jumpstart_tabular_classification/Amazon_JumpStart_Tabular_Classification_LightGBM_CatBoost.ipynb, jumpstart_tabular_regression/Amazon_JumpStart_Tabular_Regression_LightGBM_CatBoost.ipynb), XGBoost, Linear Learner (jumpstart_tabular_classification/Amazon_JumpStart_Tabular_Classification_XGBoost_LinearLearner.ipynb, and jumpstart_tabular_regression/Amazon_JumpStart_Tabular_Regression_XGBoost_LinearLearner.ipynb) and changed the keyword from JumpStart to Amazon SageMaker algorithms
Moved LightGBM, CatBoost example notebooks from previous directory JumpStart_Tabular_Regression and JumpStart_Tabular_Classification into a new directory lightgbm_catboost_tabular to be consistent with the directory structure of all the other Amazon SageMaker algorithms.
Similarly, moved XGBoost and Linear Learner example notebooks from JumpStart_Tabular_Regression and JumpStart_Tabular_Classification into a new directory xgboost_linear_learner_tabular to be consistent with the directory structure of all the other Amazon SageMaker algorithms.

Merge Checklist

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[ ] I have read the CONTRIBUTING doc and adhered to the example notebook best practices
[ ] I have updated any necessary documentation, including READMEs
[ ] I have tested my notebook(s) and ensured it runs end-to-end
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