Add user auth using Keycloak

[FelixTJDietrich]

Motivation

We need users, Keycloak offers good user management

Description

• Use oauth2 resource server together with Keycloak
• Refactor header and footer
• Improve header for better responsiveness
• Collapse "Request a feature" to icon and add tooltip on small window sizes
• Improve responsiveness of leaderboard + add an error alert if an error occured

TODO in this PR

• Add development Keycloak realm and users + admin account
• Keycloak setup for production
  • I guess we will have one instance for all deployments, a production realm and maybe test server realms
• Angular environment for Keycloak setup

Screenshots (if applicable)

Checklist

General

• PR title is clear and descriptive
• PR description explains the purpose and changes
• Code follows project coding standards
• Self-review of the code has been done
• Changes have been tested locally
• Screenshots have been attached (if applicable)
• Documentation has been updated (if applicable)

Client (if applicable)

• UI changes look good on all screen sizes and browsers
• No console errors or warnings
• User experience and accessibility have been tested
• Added Storybook stories for new components
• Components follow design system guidelines (if applicable)

Server (if applicable)

• Code is performant and follows best practices
• No security vulnerabilities introduced
• Proper error handling has been implemented
• Added tests for new functionality
• Changes have been tested in different environments (if applicable)

[FelixTJDietrich]

I looked over the code a few times and I think I got everything working, will merge now. If something is broken we will fix it in a follow-up. I want to test if the keycloak instance I setup works on develop :)