Since commit 4ef974e6cb (CPack: Remove undocumented deprecated OSXX11
generator, 2021-11-05), the `CPack.OSXScriptLauncher.in` binary is no
longer installed in the `CMake.app` bundle, so it does not need to be
signed.
We produce macOS binaries for `cmake.org` using GitLab CI jobs.
Binaries for official releases are additionally signed and notarized
manually by a maintainer with suitable signing certificates and Apple
developer account credentials. Add a script to drive these steps.