ECK 3.5: Dynamic namespaces, pause orchestration, and mTLS everywhere

ECK 3.5 introduces dynamic namespace management using Kubernetes label selectors, enabling live onboarding/offboarding of namespaces without operator restarts. It adds a 'pause orchestration' annotation for safe maintenance windows, extending mutual TLS to all stack components connecting to Elasticsearch. StackConfigPolicy is enhanced with declarative Elasticsearch role definitions and dynamic substitution variables from ConfigMaps/Secrets.