DRTVWR-474, MAINT-9047: Display top-level app bundle in sparseimage.

codesign claims to succeed, but spctl says:
/Volumes/Second Life Installer/Second Life Test.app: rejected
(the code is valid but does not seem to be an app)

Why not? Display what's in Second Life.app/Contents on the mounted
sparseimage: show Info.plist, list Frameworks, MacOS, Resources.