Sign macOS application bundles with Apple Developer certificate

[dliessi]

Signing with an Apple Developer certificate adds some security for the user and makes macOS's Gatekeeper happy, avoiding the need for the user to give special permission to run the application (see https://support.apple.com/en-us/HT202491).
However it requires to have a paid Apple Developer subscription (99$/year).

There is also the possibility of signing with a non-Apple certificate, but that's unusual and still has a cost.

See the following links for more information (thanks to @nodevnul):

• https://lapcatsoftware.com/articles/hardened-runtime-sandboxing.html
• https://eclecticlight.co/2019/01/15/code-signing-for-the-concerned-1-why/
• https://eclecticlight.co/2019/01/17/code-signing-for-the-concerned-3-signing-an-app/
• https://eclecticlight.co/2020/08/22/apple-silicon-macs-will-require-signed-code/
• https://eclecticlight.co/2020/11/03/code-signatures-3-fixing-signature-problems/

I consider this low priority until we can build a fully functional application bundle (see #1244).

See also #1576.