* s3: apply Range to HeadObject
* s3: apply Range to a HEAD of a stored directory key
Directory-key entries answer through serveDirectoryContent before
HeadObjectHandler's range branch, so a ranged HEAD returned 200 and the
full length.
* s3: keep the missing-directory check for plain directories only
A stored directory-key marker is an object, so a range on its empty body
answers 416 like on any other zero-byte object.
* s3: let partNumber keep its priority over Range on a directory key HEAD
* s3: serve ranged GETs of a stored directory key
The same branch now applies the validated range to the inline content on
GET, so a directory-key object answers 206 with the selected bytes like
any other object.
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Co-authored-by: Chris Lu <chrislusf@users.noreply.github.com>
patrickandGitHub