Dataverse collection linking/unlinking without superuser status

[vera]

What this PR does / why we need it:

Dataverse collection linking and unlinking no longer requires superuser status. Users with the "Link Dataverse" permission on a collection can now perform these actions through both the UI and API.

This change follows up on the introduction of the "Link Dataverse" permission. Previously, even with this permission, only superusers could actually perform linking actions, as reported in #12076.

• Removed the superuser requirement for linking and unlinking Dataverse collections. (Updated the LinkDataverseCommand and DeleteDataverseLinkingDataverseCommand to use the LinkDataverse permission instead of a superuser check.)
• Enabled the "Link" button in the Dataverse collection UI for non-superusers.
• Updated documentation and integration tests to reflect these changes.
• Fixed a bug in the linking service and API (discovered during testing) where the "linking" and "linked" collections were being mixed up during lookups and deletions.

Which issue(s) this PR closes:

• Closes Dataverse linking still requires superuser despite introduction of LinkDataverse permission #12076

Special notes for your reviewer:

/

Suggestions on how to test this:

I've updated the following test:

mvn test -Dtest="LinkIT#testCreateDeleteDataverseLink"

Does this PR introduce a user interface change? If mockups are available, please link/include them here:

No

Is there a release notes update needed for this change?:

I added a release note

Additional documentation:

/