emacs: Consistently use configured sort order

emacs: Consistently use configured sort order

Previously, if `notmuch-search' was called interactively (bound to "s"
in search and show, but not hello), it would always use newest-first.
However, `notmuch-hello-search' (bound to "s" in hello) and
`notmuch-hello-widget-search` would call it with the user-configured
sort order.  This inconsistency seems unintentional, so change
`notmuch-search' to use the user-configured sort order when called
interactively.