[macOS] feedback example only works when audio device is selected in macOS settings

[steckes]

When you select the same audio device in macOS settings and in CPAL, the feedback example is working. When you select another audio device in macOS settings then in CPAL, the feedback example is crashing.

Reproduce: Working:

• Select "MacBook Air Speakers" in macOS as output.
• Start Feedback Example: cargo run --release --example feedback -- -i "BlackHole 2ch" -o "MacBook Air Speakers"

Not Working:

• Select "BlackHole 2ch" in macOS as output.
• Start Feedback Example: cargo run --release --example feedback -- -i "BlackHole 2ch" -o "MacBook Air Speakers"
• Crashes with: thread 'main' panicked at 'failed to find output device'

[steckes]

I was looking back into it as we wanted to use CPAL for an audio engine, but unfortunately it is still the case, that when starting my application only virtual devices are always shown (BlackHole etc) but System Devices like External Headphones or Speakers get only shown when they were previously selected as the output device in macos.