This allows mailsync to be called like this `bindsym $mod+e exec --no-startup-id mailsync; exec $term -e neomutt && pkill -RTMIN+12 i3blocks` such that it refreshes your mail when you open mutt without it needlessly syncing if a sync is already running.

Resolves https://github.com/LukeSmithxyz/mutt-wizard/issues/197.

If -a is passed along with "$@", mailsync will sync all mailboxes even
if only a single channel is passed in with "$@". This breaks the
semantics of the `o` macro in mutt which should only sync the current
mailbox that is currently being viewed in mutt.