Consider using Pa_IsFormatSupported for probing sample rates

[dechamps]

Currently FlexASIO implements CanSampleRate by attempting to open an actual PortAudio stream and see what happens:

FlexASIO/src/flexasio/FlexASIO/flexasio.cpp

Lines 658 to 660 in 57e14e8

	Log() << "Checking if input supports this sample rate";
	OpenStream(true, false, sampleRate, paFramesPerBufferUnspecified, NoOpStreamCallback, nullptr);
	Log() << "Input supports this sample rate";

It is not clear why FlexASIO is not using Pa_IsFormatSupported() instead, which is precisely aimed at this use case - for example the pa_devs PortAudio example uses it to… well, probe sample rates.

I suspect this was an oversight on my part - it's possible I didn't realize this PortAudio function existed when I wrote the code.

Using Pa_IsFormatSupported() might be less disruptive and more efficient than opening a stream.

[dechamps]

It's possible this would work around #159 as a side effect.

[dechamps]

This is implemented in FlexASIO 1.10.