Automatically disable FrankenPHP worker mode locally

[Radiergummi]

This PR updates the FrankenPHP configuration to disable worker mode if the application is running in the local environment and the worker count is not specified explicitly (or set to auto).

The problem

FrankenPHP's Worker mode keeps the application in memory, which does wonders for performance when running in production. Locally, however, it causes problems with XDebug, and does not reflect file changes immediately. The solution to the latter is configuring Octane to restart the worker after every request, thereby defeating most of the advantages of an application server in the first place.

The solution

By only enabling worker mode if the application is running in a non-local environment, it will be served in a CGI-like manner, i.e. what the built-in PHP server (used in artisan serve) does—and exactly what you'd expect to happen: XDebug just works, and changes to files are reflected immediately.
In production, worker mode will be enabled and all the benefits that come with it apply. We use the setup as provided in this PR in our production application and don't face any issues with it.

This solves dunglas/frankenphp#931, and probably solves #928 too.

[github-actions]

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[miguno]

@Radiergummi : I am running into the same issue as dunglas/frankenphp#931. What's the status of this PR? Was the issue fixed elsewhere in the meantime?

Edit: It seems there is an updated PR at #932.

[Radiergummi]

@miguno that one's on me—it took me some time to implement some required changes—sorry. As soon as the updates have been reviewed, this should be working!

[miguno]

No worries, thanks a lot for your work on fixing this problem!