Add delta update attributes for validating an app hasn't been stripped

[zorgiepoo]

It is valid for users to strip localization files in an app bundle or strip mach-o architectures from binaries inside the app. Neither of these things if done properly invalidate an app bundle's code signature. However from a delta update's point of view, this will invalidate being able to apply a delta update, which will result in a full download after failing to apply a delta.

We could potentially do better by not even downloading delta updates (which we know will fail to apply) in this case. We could add attributes such as Sparkle's expected executable size and a partial sample handful of Sparkle's expected *.lproj locale directories. We can then validate the expected sizes or presence of these, and if they fail our expectation, then skip downloading the delta update.

For example: sparkle:deltaFromSparkleExecutableSize="1779328" sparkle:deltaFromSparkleLocales="en,ca,fr,hr,hu"