Adds compatibility for OCP (openshift container platform) and ICP (IBM cloud private)
- Sets folder permissions to group 0, because the arbitrary assigned user ids in openshift are all part of group 0
- Removes usage of root user 0, because it is prohibited in some environments
- Use numerical user id, because some environments do not accept non-numerical user ids
- Removes initContainer for setting volume permissions, because it is not needed anymore
- Removes chown in plugin script, because it is not needed anymore
- Adds extraArgs option in Helm chart to add arguments on server startup, i.e. initial admin username and password
Signed-off-by: pmarkiewka <philipp.markiewka@cloudogu.com>
