Add -assets-links-name and -assets-links-url to create release command

As part of gitlab#36133 (closed), the Release CLI needs to support creating a release with link assets. For example,

release-cli create --assets-links-name "Asset 1" --assets-links-url "url1" --assets-links-name "Asset 2" --assets-links-url "url2"

Where both --assets-links-name and --assets-links-url need to come in pairs. This matches the API requirements.

This issue will not support assets:links:filepath nor assets:links:link_type yet, as described in the Releases API documentation.

Implementation

• Add the assets fields to the JSON request made to the Releases API by the GitLab client.
• Add flags --assets-links-name and --assets-links-url to the create command.