feat: Enhanced Asset Change Detection in Shorebird

[WafikSleim]

Description

When attempting to patch an iOS app using Shorebird, a warning appears indicating that asset changes will not be included in the patch:

[WARN] Your app contains asset changes, which will not be included in the patch.
    Changed files:
        Products/Applications/Runner.app/Assets.car

However, no detailed diff is provided for Assets.car, making it difficult to determine what has changed. This issue arises even when no intentional modifications have been made to icons or other assets, leading to unexpected warnings.

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Requirements

• Implement a method to generate a detailed diff for Assets.car using xcrun --sdk iphoneos assetutil --info Assets.car or a similar tool.
• Include the diff output in the warning message when asset changes are detected.
• Enable developers to easily identify what specific changes triggered the warning.
• Update documentation to reflect this new feature, providing guidance on interpreting and resolving asset differences.
• Display the Shorebird version used in the last release for better tracking and troubleshooting.
• Allow developers to pull a specified Shorebird version to prevent compatibility issues.

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Additional Context

• This feature would significantly improve troubleshooting for developers facing unexpected asset change warnings while patching iOS apps.
• The request stems from a real-world case where a minor update (modifying parameters in a URL launcher) triggered the warning, despite no intentional changes to assets.
• Existing documentation mentions asset change warnings but does not provide a way to inspect the differences, making issue resolution more challenging.

[eseidel]

Thanks for the report!