The new Sitefinity AdminApp interface does not provide such an extension point and the ability to register custom filters.
A feature request can be logged through the Sitefinity Feedback Portal. Customer feedback is valuable and feature requests are monitored by our Product Management team. Feature requests are reviewed during the planning phase of each new product release. Once a feature request is submitted the Sitefinity Community will have the opportunity to comment on and vote for the feature request.
For detailed information on how to submit a Feature request, please refer to Progress Knowledge Base article 000074190, How to submit a Sitefinity feature request