[Bug] Product Details Last Updated is not updated when the objects change

[tylere]

Description of Bug:

The Last Updated date for a product does not update when new objects are added.

Steps to Reproduce:

• Step 1 - Enter Edit Mode on a data product you own
• Step 2 - Upload a directory

Expected Behavior:

The Last Updated value should change to the current date.

Actual Behavior:

The Last Updated value does not change.

[jedsundwall]

This should update whenever actual data or metadata change. I think it would be too confusing to have separate fields for Last Updated - Metadata and Last Updated - Data because metadata can reside in objects or in Source's own catalog. I imagine we'll have to figure out if/how we may choose to show records of changes to products in the future.

[tylere]

Tracking object entity tags (ETags) may be helpful:
https://docs.aws.amazon.com/AmazonS3/latest/API/API_Object.html
Most S3-like object stores seem to have them.

[alukach]

This seems like it will probably be downstream from us having some sort of cataloging solution wherein we are able to keep better track of the objects within a product (/cc @saulpw).