This reverts commit a878b5a.

This reverts commit 33cf264.

this is a try to fix the chaos `Never` introduced inside this library,
there is a high chance change below is the final source.
swiftlang/swift#64899

At least unit test passes after it removed.

There are also some resulting issues fixed in this commit too.

Issue is: now fileUrl generate random file urls for the same request,
cause the digest of request body is random.

There is a breaking change in swift Foundation's JSONEncoder,
sortedKeys needed now.

For detail, check here: https://developer.apple.com/forums/thread/735895