Healthview: display snapshots older than 30 days

[olivierlambert]

This feature will allow to quickly find leftover snapshots. It should filter on snaps automatically created from XO (eg backup with long retention keeping more than 30 days old snaps).

It could be displayed as a new card new the previous snapshot info card in the health view.

Original request: https://xcp-ng.org/forum/topic/10266/manual-snapshots-retention

[Jarli01]

To clarify, as there may be a translation or mix up, this view should show VM snapshots that are not created by any scheduled or automated backup process, and are older than 30 days.

The intended purpose is to validate that no single snapshot that is created by an XO Administrator is getting "to old" and should be purged, while not automatically purging these snapshots as there may be a legal requirement to keep it around for longer.

Ideally any "Notes" on the snapshot would indicate it's purpose for the XO Administrative team, but who knows...

IE
Virtual Machine | Date Created | Creator
XCP-NG-VM1 | MM/DD/YYYY:HH:MM:SS | Jerry from IT