Add "Event-Driven Ansible Content" to list of predefined tags

There is a list of predefined tags in the galaxy importer:
https://github.com/ansible/galaxy-importer/blob/5fa74a70d41de5298cf24db63618b18cd120d09e/galaxy_importer/schema.py#L43-L55
A collection has to have at least 1 of those tags to get imported (can be disabled via check_required_tags)

To support the new landing page for the Hub Dashboard, we need to update this list to include "Event-Driven Ansible Content" as a predefined tag. This will enable collection authors to tag their EDA collections with the appropriate tag so that we can display EDA related collections in a section of their own on the dashboard.