Code signing and notarization for MacOS

[cboulay]

I just re-enrolled for the Apple Developer Program. It's been 13 years since I last paid the apple developer fee.
Assuming everything goes smoothly there, I'm going to try to build a signed-and-notarized LabRecorder.app via GHA for CI/CD.

Here are some resources:

• GHA older: https://medium.com/better-programming/indie-mac-app-devops-with-github-actions-b16764a3ebe7
• GHA newer: https://federicoterzi.com/blog/automatic-code-signing-and-notarization-for-macos-apps-using-github-actions/
• CMake simple: https://github.com/tony-go/codesign-macos
• CMake complex (includes Qt support): https://github.com/supercollider/supercollider/blob/develop/editors/sc-ide/CMakeLists.txt

There's going to be some tension between code signing via CMake for local development and delaying code signing until GHA scripts.