With #239 the three ini settings on top level got stored inside a
section named identical to the setting itself. With the previous commit
they got not processed at all.
This change ensures they are taken into account on app.ini creation and
stored at the correct ini level.
Instead of rendering values into the executed script, a separate secret
resource stores all values.yaml (inline) settings for Gitea so that they
can be loaded like additional config sources are.
