Describe your changes

This PR adds an example app which subscribes to a list of signals (from a json file) and prints the values + timestamps of the signals.

Issue ticket number and link

[ ] Examples are executing successfully -> Example setup is outdated and not runnable currently. To test it, copy the code to the vehicle-app-python-template repository and execute it there in the devcontainer.
[x] Created/updated unit tests. Code Coverage percentage on new code shall be >= 80%. -> No unit tests needed
[x] Created/updated integration tests. -> No unit tests needed
[x] Devcontainer can be opened successfully
[ ] Devcontainer can be opened successfully behind a corporate proxy -> Can't test
[x] Devcontainer can be re-built successfully
[x] Extended the documentation (e.g. README.md, CONTRIBUTING.md, Velocitas) -> Added a README for the new example app