Allow meta-data expressions of the form "${node:geohash}" to be used to compute geo-hashes of the lat/lon associated with the target node.

Using this, we can add tags to time series data that contain the geohash: org.opennms.timeseries.tin.metatags.tag.geohash=${node:geohash}

And display metrics on Worldmap:
https://community.grafana.com/t/worldmap-panel-with-prometheus-metrics/5137/3