Website redesign

[DenizUgur]

This PR redesigns the MP4RA website. The underlying framework has been switched to Next.js which uses React.js. It also fixes #2, fixes #156, fixes #160.

Things to do before merge:

• [x] Add a Deploy Key and the private key as Repository Secret with the name of SSH_PRIVATE_KEY
• [x] Ensure the permissions under Actions > General for Workflow Permissions are R/W and the checkbox for GitHub Actions to create and approve PRs is on

[DenizUgur]

@podborski Are there anything that needs to be added to this PR?