Added Image to base64 convertor and vice-versa

[pranav6670]

Description

Implemented a converter that converts an image into base64 encoding and also decoding it writes to the image. Also, added a metric popularly called a structural similarity index(SSI) to compare original and new(generated) image.

Fixes #(47)

Type of change

Choosing one or more options from the following as per the nature of your Pull request.

• NOTE: These boxes can be checked using [X]

• Bug fix (non-breaking change which fixes an issue)

• New feature (non-breaking change which adds functionality)

• Documentation Update

Checklist:

Please tick all the boxes that are fulfilled by your Pull Request.

• I have named my files and folder, according to this project's guidelines.
• My code follows the style guidelines of this project.
• My Pull Request has a descriptive title. (not a vague title like Update index.md)
• I have commented on my code, particularly in hard-to-understand areas.
• I have created a helpful and easy to understand README.md, according to the given README_TEMPLATE.
• I have included a requirements.txt file (if external libraries are required.)
• My changes do not produce any warnings.
• I have added a working sample/screenshot of the script.

[pranav6670]

Please review the PR @AdityaJ7 @chavarera. Thank You!

[AdityaJ7]

@all-contributors please add @pranav6670 for code

[allcontributors]

@AdityaJ7

I've put up a pull request to add @pranav6670! 🎉

[pranav6670]

Please add a hacktoberfest-accepted label. Thank You @AdityaJ7 @chavarera

[AdityaJ7]

Please add a hacktoberfest-accepted label. Thank You @AdityaJ7 @chavarera

only required from 3 October yours was merged before that, still adding it