The unencoding stack is added to as Transfer-Encoding and
Content-Encoding fields are encountered with no distinction between the
two, meaning the stack will be incorrect if, e.g., the message has both
fields and a non-chunked Transfer-Encoding comes first. This commit
fixes this by ordering the stack with transfer encodings first.

Reviewed-by: Patrick Monnerat
Closes #10187

CVE-2023-23916
Signed-off-by: Nzhouhaifeng <kutcher.zhou@huawei.com>