This should be an optional feature, off by default. When enabled, rules like AddTypeToConstRector should run even on final classes.
Devs often want to use more such type coverage features in Rector, but making everything final is way too much work just to try it out.

Let's make upgrades a bit more easier by adding this option 🤗

return RectorConfig::configure()
    ->treatClassesAsFinal()

@samsonasik Could you kick this off?