[GDI - ckanext-dcat] Remove gdi-userportal-ckanext-dcat

[brunopacheco1]

What

Stop using gdi-userportal-ckanext-dcat.

Why

To reduce the number of repositories we need to manage, if there is not commit that make this code relevant.

Acceptance Criteria

• Is gdi-userportal-ckan-docker updated?
• Is this fork deleted?

Tasks

• Replace https://github.com/GenomicDataInfrastructure/gdi-userportal-ckanext-dcat by https://github.com/ckan/ckanext-dcat
• Delete this fork.

[brunopacheco1]

We are archiving this repo, for future reference.