Setup Prettier

[chidexebere]

Fixes #826

This:

• Installs prettier and eslint-config-prettier dependency
• Move the formatting rules to a newly created .prettierrc file
• Add files and folders prettier should ignore using a created .prettierignore file

[vercel[bot]]

@chidexebere is attempting to deploy a commit to the OONI Team on Vercel.

A member of the Team first needs to authorize it.

[majakomel]

Closing this since we're going with biome