feat: add macro warning and aggregate corpus generation errors

[HiteshMittal07]

This PR updates auto_generate_corpora to collect failures from all targets instead of stopping at the first error. All identified failures are now reported collectively at the end of the process.

Key Changes:

• Modified auto_generate_corpora to aggregate errors into a single message.
• Added an integration test ( multiple_failures.rs ) to verify that failures from multiple targets are correctly captured and displayed together.

Fixes #677

[smoelius]

I think we can dispense with the test for this change.

[smoelius]

I would prefer that this error not be discarded.

Would it be possible to have the entries in errors be either this kind of error or the kind issued on line 1326 below?

[juice928]

👋 Hi, I'm an automated AI code review bot. I ran some checks on this PR and found 1 point that might be worth attention (could be false positives, please use your judgment):

1. Error details in corpus generation could be more visible to improve debuggability
   • cargo-test-fuzz/src/lib.rs:L1325: cargo-test-fuzz/src/lib.rs:L1325
   • Impact: Specific causes for failure (like file permissions or disk space) are currently replaced by a generic message, making troubleshooting harder.
   • Suggestion: Consider capturing the Err result from auto_generate_corpus and including it in the errors vector to provide clearer feedback to the user.

If you find these suggestions disruptive, you can reply "stop" , and I'll automatically skip this repository in the future.