Use new copy-to-repl logic when synching package and dir

* contrib/sly-mrepl.el (:copy-to-repl): renamed from
:COPY-OBJECT-TO-REPL, accepts object list.
(sly-mrepl--eval-for-repl, sly-mrepl-copy-down-to-repl): Use new
channel name
(sly-mrepl-sync-package-and-default-directory): Don't mess with
prompt here.

* contrib/swank-mrepl.lisp (copy-values-to-repl): new function.
(:sync-package-and-default-directory): Use COPY-VALUES-TO-repl.
(:copy-to-repl): Renamed from :COPY-OBJECT-TO-REPL, use
COPY-VALUES-TO-REPL.