Lint for `reg<whatever>` types outside of `pg_catalog`

[olirice]

pg_upgrade does not support upgrading of databases containing table columns using these reg* OID-referencing system data types:

• regcollation
• regconfig
• regdictionary
• regnamespace
• regoper
• regoperator
• regproc
• regprocedure

(regclass, regrole, and regtype can be upgraded.)

This task is to add a WARN lint to notify users they will not be able to upgrade their database without first removing references to those types