Improve sorting in package list (Bug#37419)

Improve sorting in package list (Bug#37419)

* lisp/emacs-lisp/package.el (package-menu-mode): Allow sorting by
version or description.
(package-menu--version-predicate): Fix sorting by version.
(package-menu--description-predicate): Fix sorting by description.
(package-menu--archive-predicate): Fall back to sorting by name if
archive is the same.
(package-menu--name-predicate, package-menu--status-predicate): Add
doc string.
* etc/NEWS: Announce the above changes.