(use com.redhat.swatch.metrics package)

• port from spring expression language to Qute templates (see https://quarkus.io/guides/qute)
• update bin/metering-promql.py to process the Qute templates
• TBD: qute alternative suggested by Jose.

Final decision was made to use a custom implementation instead of using a third-party framework like mvel2 or qute.