Change wlr_output_layout_move to wlr_output_layout_add

[kuruczgy]

Upstream is removing wlr_output_layout_move, this is now required to build with wlroots master. (Along with #71 of course.)

See: https://gitlab.freedesktop.org/wlroots/wlroots/-/commit/097ea84cda70a71ad8ea5940b3b3d277167424e5