Add a new single_model_trainer function for training clustering problems.

[sagnik1511]

What you have to do- 1. Add a new function inside the tab_automl.automl.training.Trainer class for training clustering problems. 2. Inside the main function of tab_automl.main some implementation will be needed so that the clustering problem type fits.

Follow contributing guidelines on README.md

[Viveksati5143]

please assign me this issue