Move metadata records into a common collection

[randytpierce]

Currently our metadata (type="MD") documents are all in the METAR collection. It seems that they should be in a "METADATA" or a "COMMON" collection.

[ian-noaa]

Should this be moved back out of "in progress"? This appears to be part of #379.

[github-actions]

This issue is stale because it has been open 90 days with no activity.

[ian-noaa]

Per @mollybsmith-noaa - metadata needs to exist in both locations until MATS is switched over.

[gopa-noaa]

Please refer to this discussion on where metadata should reside.
ref: #379

Salient points below:
(We don't need COMMON collection, at least initially). Collection specific metadata can belong in their respective collections. Only metadata that describes data in a collection should belong in a collection. Other metadata is better to reside on specific metadata collection for performance reasons. . If there is a need to capture metadata (very specific) they could be in a different collection , example MD_MATS, MD_STATIONS. For now, start without COMMON collection, and if needed we can add this later.

[github-actions]

This issue is stale because it has been open 90 days with no activity.