Document jpackage Mac App Store signing.

With JDK-8248904, jpackage has added CLI options and made other changes to allow some jpackage applications to be acceptable to the Mac App Store.

This tasks seeks to document in the "Sign the Application Package (macOS)" section of "https://docs.oracle.com/en/java/javase/<version>jpackage" the 3 new cli options:
--mac-app-store, --mac-entitlements, and --mac-app-category

See https://docs.oracle.com/en/java/javase/15/jpackage/support-application-features.html#GUID-8D9F0607-91F4-4070-8823-02FCAB12238D for the "Sign the Application Package (macOS)" section.

The default entitlements with and without using --app-app-store should be itemized,
The specific difference building an app-image and/or pkg with and without --mac-app-store should be specified.
The impact and expected values of --mac-app-category should be given.

The existing doc (at least for JDK15) has an error in it in that it does not mention --mac-signing-keychain.

The sections that give examples needs to be modified to indicate what certificate(s) will be used in each case of packageing for app stroe or not, and signing app-image vs signing pkg.