Support for mounting ephemeral CSI volumes

[addreas]

Related GH Issue

Additional Information

Currently running a custom extension that requires some credentials. Mounting them via a CSI ephemeral volume would be preferable, so I added support for that here.

Checklist:

• [ ] Automated Tests
• [ ] Documentation changes if necessary
• [ ] (If required) Discussed on Keycloak DEV

[vmuzikar]

Thank you very much for you contribution. Keycloak 19 was the last version that included this legacy Operator, and with the release of Keycloak 20 the Operator reached EOL, please see our blog post on this topic. Since this PR was not ready before Keycloak 19.0.0 had been released (and we're not adding new features in micro releases), I'm closing this PR as it is no longer relevant for this Operator (or for the Realm Operator which doesn't include Keycloak CR). Thanks for your understanding. And be sure to check out our new Operator!