[Impeller] Fallback to graphics queue is transfer queue is not available

[dnfield]

On some devices (for example an Android Pixel 4), a dedicated transfer queue is not available. This should not be considered a fatal error - instead we should use the graphics queue for transfer.

Fixes flutter/flutter#123791

[flutter-dashboard]

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[chinmaygarde]

We don't use the transfer queue at all right now. Just FYI. I think we'll end up needing one eventually though.

[dnfield]

We don't use the transfer queue at all right now. Just FYI. I think we'll end up needing one eventually though.

I noticed that but wasn't sure if I was just missing something.