MacOS builds (VST3 & AU)

**If you want to request a full plugin please use the plugin request template**

**Describe the feature you'd like**
Mac builds.

**Is your feature request related to a problem? Please describe.**
 - No access to compatible hardware.
 - No access to testing environment.

**Describe alternatives you've considered**
 - GitHub actions. But the plugins will be untested and won't be signed.

