CMake support, modernized rnnoise example with libsoundfile and CI setup based on Github Actions

[ValentiWorkLearning]

Thanks for this great work over this library. I've decided to add CMake support for rnnoise and introduce CI/CD build setup for the project, since it seems to be convenient way of PRs checking for Linux/Windows builds. Also, this PR introduces slightly modernised version of rnnoise example using libsoundfile with the capability of reading WAVE files instead