RESUMABLE: proposal - change the design from server-managed to client-managed

[LPardue]

@gstrauss provided the following feedback on https://lists.w3.org/Archives/Public/ietf-http-wg/2025JulSep/0094.html wrt Section 4.2.2

This fragility could potentially be avoided if the client managed the overall upload resource state rather than the server. The client could send chunks of representation data, and then resend the whole chunk on failure. (Maybe try to recover by sending smaller chunks.) The server would manage the upload resource per-request and apply policies per-request.