Feature Request/Idea: Make sure that for datasets published with CC0 waiver or standard license, metadata exports include the waiver or license

Overview of the Feature Request
Make sure that for datasets published with a CC0 waiver or a standard license, their metadata exports include the waiver or license.

What kind of user is the feature intended for?
Curator, Guest

What inspired the request?
While reviewing the metadata exports of datasets published in repositories running a Dataverse software version that includes the "multiple license" update, I noticed that for certain datasets published before that update, the metadata exports don't include the CC0 waiver or other standard license.

For example, after the multiple license update, datasets published before that update with a CC0 waiver and metadata entered in one or more "Terms of Use" fields were updated to include text in the Terms of Use field that read that "This dataset is made available under a Creative Commons CC0 license with the following additional/modified terms and conditions":

But the OpenAIRE and Schema.org metadata exports of those datasets do not include information about the CC0 waiver:

• OpenAIRE export of dataset with CC0 waiver plus metadata entered in one or more "Terms of Use" fields
• Schema.org export of dataset with CC0 waiver plus metadata entered in one or more "Terms of Use" fields

For comparison, see the OpenAIRE and Schema.org metadata exports of a dataset with a CC0 waiver and nothing entered in any of the "Terms of Use" fields:

• OpenAIRE export of dataset with CC0 waiver and no metadata entered in one or more "Terms of Use" fields
  

• Schema.org export of dataset with CC0 waiver and no metadata entered in one or more "Terms of Use" fields
  

What existing behavior do you want changed?
For datasets that were published with a CC0 waiver (or possibly a CC-BY license for some Dataverse repositories whose default license was CC-BY), include in their metadata exports information about those waivers or licenses. This will become more important as license metadata is included in more exports (e.g. being sent to DataCite (https://github.com/IQSS/dataverse/issues/5889)) and is indexed and made searchable (e.g. https://github.com/IQSS/dataverse/issues/7482).

Start by comparing the OpenAIRE and Schema.org export endpoints linked in the issue for datasets with and without Terms of Use metadata. Trace how published CC0 waivers and standard licenses reach these exporters; done means both exports include the applicable waiver or license for affected datasets.