Propagate error to active chunk subscriber in SplittingPublisher

[davidh44]

Motivation and Context

Fixed bug where SplittingPublisher.onError() did not signal the active SubAsyncRequestBody, causing its subscriber to hang until timeout instead of being notified immediately

Modifications

• Call currentBody.error(t) in SplittingSubscriber.onError()
• Add error(Throwable) to SubAsyncRequestBody interface
  - Implement error() in RetryableSubAsyncRequestBody
  - Override error() in NonRetryableSubAsyncRequestBody

Testing

Added unit test

Screenshots (if appropriate)

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)

Checklist

• I have read the CONTRIBUTING document
• Local run of mvn install succeeds
• My code follows the code style of this project
• My change requires a change to the Javadoc documentation
• I have updated the Javadoc documentation accordingly
• I have added tests to cover my changes
• All new and existing tests passed
• I have added a changelog entry. Adding a new entry must be accomplished by running the scripts/new-change script and following the instructions. Commit the new file created by the script in .changes/next-release with your changes.
• My change is to implement 1.11 parity feature and I have updated LaunchChangelog

License

• I confirm that this pull request can be released under the Apache 2 license