gh-128192: support HTTP sha-256 digest authentication as per RFC-7617 (GH-128193) support sha-256 digest authentication Co-authored-by: Peter Bierma <zintensitydev@gmail.com> Co-authored-by: Bénédikt Tran <10796600+picnixz@users.noreply.github.com> Co-authored-by: Gregory P. Smith <greg@krypto.org>