Fix presigned url multipart download for empty objects

[jencymaryjoseph]

Motivation and Context

Presigned URL multipart downloads fail with HTTP 416 (Range Not Satisfiable) when downloading zero-byte objects. The multipart subscriber sends Range: bytes=0-8388607 to request the first part, but for a zero-byte object there are no bytes in that range, so S3 returns 416 per the HTTP spec.
Normal (non-presigned) multipart downloads don't have this issue because they use partNumber=1 as a query parameter. S3 treats this differently — it returns 200 with Content-Length: 0 for empty objects, because "give me part 1" is valid even when the part is empty.
The difference is the mechanism: Range headers require the byte range to exist (fails for empty objects), while partNumber returns the part content regardless (succeeds with empty body).

Modifications

When the first range request returns 416, the helper catches it and falls back to a non-range GET using the same presigned URL. The non-range GET succeeds for empty objects (returns 200 with Content-Length: 0), and the response flows through the normal transformer path — creating the file and returning full metadata.
A marker exception (EmptyObjectRangeNotSatisfiableException) distinguishes 416 on the first request (empty object, safe to fallback) from 416 on subsequent requests (real error that should propagate). Subscribers wrap the 416 in this marker only on the first request. The helper only triggers the fallback for this marker — all other errors propagate normally.

• PresignedUrlDownloadHelper: Added 416 fallback logic in downloadObject(), extracted doMultipartDownload(), added isRangeNotSatisfiable() and EmptyObjectRangeNotSatisfiableException marker class.
• PresignedUrlMultipartDownloaderSubscriber: Wraps 416 on partIndex == 0 with marker exception instead of calling handleError.
• ParallelPresignedUrlMultipartDownloaderSubscriber: Wraps 416 in sendFirstRequest with marker exception. Removed forwardExceptionTo from sendFirstRequest to prevent race with the wrapping logic.

Testing

• PresignedUrlMultipartDownloaderSubscriberWiremockTest: Added tests for 416 fallback on first request, error propagation on subsequent request, and user-specified range on empty object.
• ParallelPresignedUrlMultipartDownloaderSubscriberTest: Added tests for 416 fallback on first request and error propagation on subsequent request for the parallel (toFile) path.
• AsyncPresignedUrlExtensionTestSuite: Added integration tests for zero-byte object download (toBytes and toFile) and user-specified range on empty object. Runs for both multipart and non-multipart clients.

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
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• I have updated the Javadoc documentation accordingly
• I have added tests to cover my changes
• All new and existing tests passed
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• 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