V15: Dont delete when referenced setting is enabled

[Zeegaan]

Notes

• We would not respect the ContentSettings.DisableDeleteWhenReferenced & ContentSettings.DisableDeleteWhenReferenced
• This PR remedies that, by checking for the setting, and then using the relation service, to see if a given item is related.

How to test

• Create a Document type with allowed as root set to true, create a "root" document from that
• Create another document type with allowed as root set to true, AND a content picker property.
• Create a document with the 2nd document type, and make sure to pick your first content with the content picker.
• Stop the application
• Overwrite the content section in your appsettings.json

      "Content": {
        "DisableDeleteWhenReferenced": true,
        "DisableUnpublishWhenReferenced": true,
        "Notifications": {
          "Email": "[email protected]"
        },
        "MacroErrors": "Throw"
      },

• Run the application
• Try to trash the referenced content, you should not be able to
• Try to unpublish the referenced content, you should not be able to
• Set "DisableUnpublishWhenReferenced": false,
• Restart the app
• Try to trash the referenced content, you should now be allowed
• Try to remove it from the recycle bin, that should not be allowed

[kjac]

Works like a charm 💪