Allow event triggers on publications, foreign data wrappers and extensions.

[steve-chavez]

Problem

This limitation is due to implementation details, since supautils has to switch to supautils.superuser when creating the above database objects, and we have to skip privileged role event triggers here to avoid privilege escalation.

Solution

Might be possible to execute the event trigger function ourselves when those statements are executed.

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Labeling this as "minor" since it doesn't seem like critical functionality (event triggers currently work fine for regular db objects like tables, views, functions, etc).