[0.5.x] Improve forgetFiles to handle nested structures and edge cases

[rottifant]

Changes:

• Recursive File Detection:

  • forgetFiles now supports recursive detection of files in deeply nested objects and arrays.
  • Fixes Files in nested objects are sent during validation #114.

• Improved Compatibility with Non-Iterable Objects:

  • Utilizes Object.getOwnPropertyNames to ensure compatibility with non-iterable objects, allowing files in such objects to be detected reliably.

• Backward Compatibility:

  • The function remains compatible with existing features and use cases.
  • The updated logic does not change the behavior for flat or simple structures but corrects previous incorrect behavior.

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• Ensures that file uploads in complex payloads are accurately detected, even when files are deeply nested within other data.
• No breaking changes, making it easy for users to adopt the updated functionality.

[rottifant]

@timacdonald What's the current status? If I can help anything, please let me know.