Activity and Workflow lookup does not work with autoload

I'm trying to implement Rails' autoloading feature in my local development so I can avoid restarting the workers every time I make a code change. This was easily achieved with a middleware
```
class ReloaderMiddleware
def call(_, &block)
::Rails.application.reloader.wrap(&block)
end
end
```

However, any `Temporal::Workflow` and `Temporal::Activity` class definition are cached in memory at registration time by `ExecutableLookup`, so changes in those particular classes are not reflected when the code reloads. It would be really nice to offer an option to reload those classes at run time, and make it optionally available only during development.