Support time_series_metric attribute in schema and generated artifacts

[ebeahan]

Summary

Support the time_series_metric mapping parameter on numeric field types in the ECS field definitions and necessary generated artifacts.

This addition helps ECS better support time series data streams (TSDS).

Requirements

• The time_series_metric attribute is supported in ECS schema definitions. Example definition:

- name: host.cpu.system.norm.pct
  type: double
  # Support this requires an Elasticsearch version on 8.6 or newer
  time_series_metric: gauge
  description: >
    The normalised percentage of CPU time spent in kernel space.

• time_series_metric matches the ES implementation and supports three value for numeric fields: counter, guage, and null.
• The ES generator allows time_series_metric param into generated index templates where defined.
• The Beats field generator passes time_series_metric where defined.