Cannot open Crystal on macOS 11 by default, without overriding security settings

[davidfstr]

Priority: High

• Prevents first-run for the average end-user on macOS 11.

Repro Steps:

• Run Crystal binary on fresh macOS 11.

Expected Results:

• Program runs.

Actual Results:

• macOS displays a security prompt complaining "the developer cannot be verified" and refuses to launch the app.

Workaround:

• Right-click or Control-click on the Crystal app and select Open to open Crystal. Then a new button will appear in the security prompt which will allow you to open the app anyway. Click it.

Tasks:

• Build app binary for Mac App Store, signed with Developer ID certificate, although no need to actually submit the app to the store just to fix the security warning ⏳