Create default Action type: petitions

Summary

We use the Action type for setting permalink structure for Actions and fallback to Action slug in case there is none defined. To avoid permalink changes once Actions are initially enabled, we could create a default Action type already. That would also serve as a visual cue for admins to use/change it.

Requirements

• Create "Petitions" (with slug petitions) Action type and set it as the default one.
• Skip creating that if Action types already exist in a website.