added image classification using transformer feature notebook

Description

I have added a pynb which contains inference code for image classification using transformer. The pipeline provides a checkpoint which can be downloaded and used for adding new classes and fine tuning, a test image and the a json file of ImageNet classes. The user need not worry about the required files. The code downloads all the required file from my S3 bucket. This is a pulg-and-play notebook.

This change is required as an issue is raised to include an image classification model which utilises transformer. This is the issue #raied: [FEATURE_REQUEST] Add vision transformers model to image classification #678

Related Issues

[FEATURE_REQUEST] Add vision transformers model to image classification #678 https://github.com/microsoft/computervision-recipes/issues/678

Checklist:

[x ] I have followed the contribution guidelines and code style for this project.
[ x] This branch is created from staging and not master.
[x ] This PR is being made to staging and not master.
[ x] I will squash merge this PR into staging.
[ x] I have added tests covering my contributions.
[x ] I have updated the documentation accordingly.

microsoft / computervision-recipes