Implement Helmholtz Corporate Design

Created by: cmeessen

Implements the following features:

• Imprint, closes #3 (closed)
• Data protection declaration, closes #11 (closed)
• Helmholtz Corporate Design / Landing page, closes #2 (closed)
• Helmholtz Corporate Design / all other pages, closes #4 (closed), closes #5 (closed), closes #6 (closed), closes #7 (closed), closes #8 (closed), closes #9 (closed), closes #10 (closed)

How to test:

• pull branch and recurse submodules

  git checkout feature-helmholtz-corporate-design --recurse-submodules

• copy .env.example to .env and fill in the required information
  • remember to add yourself to RSD_ADMIN_EMAIL_LIST
  • set RSD_AUTH_PROVIDERS=HELMHOLTZAAI
  • if you need the AAI secret, ask @ruester or @cmeessen
• build

  make dev

• if you want to migrate some data, go to this repo, clone it to a different location, and follow the instructions to migrate the latest software spotlights to your local RSD
• access the RSD via http://localhost:3000

To do's:

• Finalise imprint
• Add hard coded software spotlights on the front page
• Provide text content for the front page

PR Checklist:

• Increase version numbers in docker-compose.yml
• Link to a GitHub issue
• Update documentation
• Tests