This mainly means the keycloak config moves to a separate bundle

The core bundle is now available on packagist

While the starter bundle gives a nice example for how to integrate an API
it makes setting up a new server harder because the user usually already
has a bundle in mind that he/she wants to add.

So remove it and instead make it easier to add bundles by improving the docs

This is now handled by the composer.json in .gitlab-ci if needed

symfony now requires framework.secret to be set
the person entity is gone from the core bundle, so no need to implement it.

The starter bundle gained an example configuration and this adds an example
config file to set it.

While we directed the docker image to translate the URLs to https anyway
this can be confusing since git behaves differently in docker vs outside.

Also in the meantime we have made all repos public, so there is no auth needed
for the repos and the extra work required using https no longer applies.