Investigate soxr as a replacement resampling library

[tmiw]

Continuation of PR #776 with the changes needed to switch from libsamplerate to soxr as the resampler.

TODO:

• Develop test procedure for comparing soxr with libsamplerate
• Test soxr at various quality levels against existing libsamplerate code
• TBD

[drowe67]

@tmiw - I do not feel there is any justification for this PR - and the decision to do this work should be a decision made by the PLT.

Resamplers are not magic and we are not going to get significant improvements by swapping libraries in and out. A much better approach is our own, well understood resamplers, as per #777.

[tmiw]

We can close, but I'd say not to delete this branch in case we decide to start working on #777 at some point in the future and find that the soxr work already done may be useful (which might not be if we find that another strategy is better, of course).