GN-4958: add snippet node and nodeview to regulatory-statement editor config

[elpoelma]

Overview

This PR ensures that the snippet node-spec and nodeview are correctly added to the regulatory-statement editor configuration.

connected issues and PRs:

GN-4958

How to test/reproduce

• Open the application
• Create a regulatory statement based on a template which contains snippet placeholders
• You should be able to use the snippet placeholder to insert a snippet without issues

Checks PR readiness

• UI: works on smaller screen sizes
• UI: feedback for any loading/error states
• Check cancel/go-back flows
• Check database state correct when deleting/updating (especially regarding relationships)
• changelog
• npm lint
• no new deprecations