## Problem
This PR works on adding dynamic masking support for `anon` v2. It
currently only supports static masking.
## Summary of changes
Added a security definer function that sets the dynamic masking guc to
`true` with superuser permissions.
Added a security definer function that adds `anon` to
`session_preload_libraries` if it's not already present.
Related to: https://github.com/neondatabase/cloud/issues/20456