log_to_metric tag expansion

[arch-xtof]

I couldn't find any way/example to use log_to_metric transformation with dynamic tag names. Having something similar to label expansion from the Loki sink will be useful.

This way it would be possible to define labels in this fashion:

[transforms.count_metrics.metrics.tags]
"*"  = "{{ labels }}"

Similarly to Loki:

[sinks.loki.labels]
"*" = "{{ labels }}"

[arch-xtof]

Right now I send them to the different transform to achieve this.

[transforms.count_metrics_fixed]
  type = "remap"
  inputs = ["count_metrics"]
  source = '''
    .tags = merge(.tags, parse_json!(.tags.other_labels)) ?? .tags
    del(.tags.other_labels)
  '''