Many DataObjects are missing class_description config

[emteknetnz]

Split from #11603

When running the text collector task it was noticed that a large number of DataObjects were missing the class_description config

A few examples

• SilverStripe\LinkField\Models\EmailLink
• SilverStripe\CMS\Model\SiteTreeLink
• SilverStripe\UserForms\Model\EditableCustomRule

Acceptance criteria

• Write a script to identify all DataObjects that are missing class_description config
• Add new class_description to these DataObjects
• Possible reverse the conditional logic added to DataObject::provideI18nEntities() in the linked PR above
• Possibly the raise notices or throw exceptions if config is missing