Fix handler calls to reference lisp-mode.
Fix handler calls to reference lisp-mode.

`set-repl-handler!` helps with opening a repl when a particular mode is
active in a buffer. We want to be able to open a `sly-mrepl` whenever we
are in a lisp buffer, so we should have the repl handler look for
`'lisp-mode` to define opening a sly repl.

I assume the lookup handlers should be making sure we are in a lisp
buffer (similar reasoning to the repl-handler).

UndeadKernel/emacs_doom,UndeadKernel/emacs_doom,hlissner/doom-emacs,UndeadKernel/emacs_doom,hlissner/.emacs.d,hlissner/.emacs.d,hlissner/doom-emacs,hlissner/.emacs.d,hlissner/.emacs.d,UndeadKernel/emacs_doom,hlissner/doom-emacs,hlissner/doom-emacs,hlissner/.emacs.d,UndeadKernel/emacs_doom,UndeadKernel/emacs_doom,UndeadKernel/emacs_doom,hlissner/.emacs.d,hlissner/doom-emacs,hlissner/doom-emacs,hlissner/.emacs.d,hlissner/doom-emacs,hlissner/.emacs.d