SSL API Change + Docs and Tutorial Update (#360)

* doc changes
added data utils
need to make changes to SSL in a separate PR

* breaking change: SSL
changed api and fixed a few bugs
made datamodule more cleaner
updated tutorials and test cases

* added new param to include input features to SSL finetuning
updated tut notebooks

* pre-commit changes

* added more tutorials

* enhanced tutorials and documentation

Author: manujosephv

.gitignore

@@ -157,3 +157,4 @@ examples/test_save/
 tests/.datasets/
 test.py
 lightning_logs/
+docs/tutorials/examples/basic/

docs/explainability.md

@@ -34,7 +34,7 @@ tabular_model.explain(test.head(1), method="GradientShap", baselines="b|10000")
 tabular_model.explain(test.head(10), method="IntegratedGradients", baselines=0)
 ```
 
-Checkout the [Captum documentation](https://captum.ai/docs/algorithms) for more details on the algorithms and the [Explainability Tutorial](tutorials/11-Explainability.ipynb) for example usage.
+Checkout the [Captum documentation](https://captum.ai/docs/algorithms) for more details on the algorithms and the [Explainability Tutorial](tutorials/14-Explainability.ipynb) for example usage.
 
 ## API Reference
 ::: pytorch_tabular.TabularModel.explain