Backup creation date needs to be saved as a field

[ormsbee]

We currently export this in a comment, but this is necessary to display in the UX for restoring the library.

This might be worth having a new metadata section in the package.toml file, to have things like:

[meta]
format_version = 1
created_by = "dormsbee"
created_at = <datetime>
origin_server = "{get this from settings.CMS_BASE}"

[learning_package]
title = "Library test"
key = "lib:WGU:LIB_C001"
description = ""
created = 2025-08-19T04:25:10.988166Z
updated = 2025-08-19T04:25:10.988166Z

[ormsbee]

Add Open edX release to the "meta" section.