* lisp/emacs-lisp/package.el: Refactor -with-work-buffer-async

* lisp/emacs-lisp/package.el: Refactor -with-work-buffer-async

(package--with-work-buffer-async): Reimplement as
`package--with-response-buffer'.
(package--with-work-buffer): Mark obsolete.
(package--with-response-buffer): New macro. This is a more self
contained and less contrived version of
`package--with-work-buffer-async'.  It uses keyword arguments,
doesn't have async on the name, doesn't fallback on
`package--with-work-buffer', and has _much_ simpler error
handling.

(package--check-signature, package--download-one-archive)
(package-install-from-archive, describe-package-1): Use it.

(package--download-and-read-archives): Let
`package--download-one-archive' take care of calling
`package--update-downloads-in-progress'.