I2S API support

[Mani-Sadhasivam]

Hello,

This issue is created for tracking the progress of I2S API support in MRAA. I will initially lead the development of the API and anyone who might be interested is welcome to join!

My first approach is to base the API support on top of ALSA lib. But since this is an external library, I'm not sure whether we can depend on it or we should implement the API from scratch.

[Mani-Sadhasivam]

@Propanu @arfoll @malikabhi05 @alext-mkrs thoughts?

[alext-mkrs]

Taking in such a [big IIRC] library as ALSA would I think go against the mraa's basic principles of trying to be independent where it makes sense. So to understand whether it does - could you please describe what use cases do you want to target?