Use an AppleConnect API key to notarize

Right now we use an Apple ID and app-specific password to notarize our application with Apple. This unnecessarily ties our builds to the permissions of an individual developer. If their permissions are reduced it could break notarization; if their permissions are increased it means our credentials are more powerful than they need to be.

`notarytool` can be configured to use an API key on the command line: https://keith.github.io/xcode-man-pages/notarytool.1.html#App

We also need an admin of our Apple Account to generate the key and add it to the GitHub Actions secrets.

Locate the GitHub Actions workflow that invokes Apple’s notarytool, then read the notarytool App authentication documentation linked in the issue. Update the notarization configuration to use an AppleConnect API key from GitHub Actions secrets, and verify that the workflow completes successfully after an Apple Account admin creates and adds the key.

Scritto dal modello di indicizzazione a partire dal testo della issue.