Add a field for a certificate draft preview link to information provided by the codechecker

[nuest]

When the codechecker publishes the certificate outside of OJS, e.g., on OSF or Zenodo, then they should be able to provide through OJS a preview link to the certificate so that editors (and authors) can inspect it before the certificate goes live.

The field should include some instructions and the links below.

• https://help.zenodo.org/docs/share/link-sharing/
• https://help.osf.io/article/201-create-a-view-only-link-for-a-project