Content-Encoding is set to "aws-chunked" which is an S3 specific
API value which is no meaning for an object. This is how S3
behaves as well for a streaming signature uploaded object.
* Refactor streaming signatureV4 w/ state machine
- Used state machine to make transitions between reading chunk header,
chunk data and trailer explicit.
* debug: add print/panic statements to gather more info on CI failure
* Persist lastChunk status between Read() on ChunkReader
... remove panic() which was added as interim aid for debugging.
* Add unit-tests to cover v4 streaming signature
Harshavardhana