Create an upgrade routine that enables External Scripts (under System Configuration) only if any General Purpose Custom Publishers exist.

For the sake of security and not confusing Appliance customers, external script routines (the External Validator and General Purpose Custom Publishers) can be set as disabled, and should be by default. For anybody running a General Purpose Custom Publisher, this will confuse the heck out of them, so we should add an upgrade routine that sets this value as enabled in case such a publisher exists. External Validators were added in 6.11.0, so they're no issue.