The release notes for Xcode 15 mentions that xcodebuild has support for automatic distribution:
xcodebuild -exportArchivesupports using App Store Connect authentication keys to upload apps to App Store Connect and the Apple notary service. (76036452)
I'm not able to find any documentation about the flags or options to pass to xcodebuild to do automatic TestFlight uploading, and it's not covered in the xcodebuild man pages either.
Can someone detail what the command-line flags are to enable this?