[Draft] Feature/automated builds

[kmturley]

This is a work in progress feature which aims to automatically build Linux, Mac and Win releases in a Github pipeline. Opening a PR for your visibility on it.

You can view workflow runs here:
https://github.com/studiorack/juicysf/runs/7710081501?check_suite_focus=true

Mac build is working locally.

Currently erroring at the step in linux:

-- Checking for one of the modules 'fluidsynth>=2'
CMake Error at cmake/Modules/FindPkgConfig.cmake:920 (message):
  None of the required 'fluidsynth>=2' found
Call Stack (most recent call first):
  CMakeLists.txt:48 (pkg_search_module)