Add free2pass Covid-19 contact tracing app (Germany)

Added German Covid 19 contact tracing app free2pass.

free2pass is developed by Hanntech GmbH for some Covid-19 model communities around Nienburg/Weser in Germany.

The source code is provided under the terms and conditions of AGPL-3.0-or-later. Build works and fastline metadata has been added to the project structure.

Link to source repo.

• The app complies with the inclusion criteria
• The original app author has been notified (We are the original developers)
• All related fdroiddata and RFP issues have been referenced in this merge request (None)
• The upstream app source code repo contains the app metadata (summary/description/images/changelog/etc) in a Fastlane or Triple-T folder structure (fastlane)
• Builds with fdroid build
• Releases are tagged