[gnome-builder] plugins/emacs: remove emacs plugin

[Christian Hergert <chergert src gnome org>]

commit 22763f61e19f2a4b8e885af776aecb4dd70c622a
Author: Christian Hergert <chergert redhat com>
Date:   Mon Jul 11 22:38:05 2022 -0700

    plugins/emacs: remove emacs plugin
    
    This doesn't really fit into how keybindings work in GTK 4 so it's quite
    a bit of effort to keep it alive. If someone can figure out a way to do
    the stateful thigns cleanly here, I'd be happy to have it back.

 src/plugins/emacs/emacs-plugin.c                |  36 ----
 src/plugins/emacs/emacs.gresource.xml           |   7 -
 src/plugins/emacs/emacs.plugin                  |   9 -
 src/plugins/emacs/gbp-emacs-preferences-addin.c |  89 ---------
 src/plugins/emacs/gbp-emacs-preferences-addin.h |  31 ----
 src/plugins/emacs/keybindings/emacs.css         | 234 ------------------------
 src/plugins/emacs/meson.build                   |  12 --
 7 files changed, 418 deletions(-)