Skip extracting auxiliary files and improve extraction progress for disk images

[zorgiepoo]

• Skip extracting auxiliary files from disk images
• Improve reporting extraction progress from disk images by monitoring how many files are copied
• Improve progress reporting in sparkle-cli slightly

Misc Checklist

• My change requires a documentation update on Sparkle's website repository
• My change requires changes to generate_appcast, generate_keys, or sign_update

Testing

I tested and verified my change by using one or multiple of these methods:

• Sparkle Test App
• Unit Tests
• My own app
• Other (please specify)

Added unit tests for extracting more disk image files (with auxiliary files or pkg file), and tested downloading/extracting disk image files with a custom app, including a disk image containing a pkg file.

macOS version tested: 14.5 (23F79)