fix(extras): handle multiple contacts and publishers with 1-based ind…

[hcvdwerf]

…exing

• Adjust contact and publisher handling to support multiple entries with 1-based indexing
• Append contact details with keys like contact_email_1, contact_uri_1, etc.
• Append publisher details with keys like publisher_uri_1, publisher_name_1, etc.
• Ensure consistent indexing when storing contact and publisher information
• Closes issue #307

[amercader]

See https://github.com/ckan/ckanext-dcat/issues/307#issuecomment-2385313502