Add prettier to project

[blocus]

PR Details

Description

I found that this project doesn't follow any code style so I added my prettier config file and I added a script to format the project.
Then I formatted the project so the new contributors could start with the same code style.

Related Issue

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• If suggesting a new feature or change, please discuss it in an issue first.
• If fixing a bug, there should be an issue describing it with steps to reproduce.
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Motivation and Context

• Why is this change required?
• What problem does it solve?

How Has This Been Tested

• Please describe in detail how you tested your changes.
• Include details of your testing environment, and the tests you ran to.
• see how your change affects other areas of the code, etc.

Types of changes

What types of changes does your code introduce? Put an x in all the boxes that apply:

• Docs change / refactoring / dependency upgrade
• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)

Checklist

• Go over all the following points, and put an x in all the boxes that apply.
• If you're unsure about any of these, don't hesitate to ask. We're here to help!

• My code follows the code style of this project.
• My change requires a change to the documentation.
• I have updated the documentation accordingly.
• I have read the CONTRIBUTING document.
• I have added tests to cover my changes.
• All new and existing tests passed.