Add Emacs desktop provisioning and dev toolchain packages

Install Emacs and copy the desktop .emacs.d config so the editor setup is managed with the rest of desktop dotfiles. Add vterm/build/debug dependencies plus C/C++ and Go tooling needed by the configured workflow.

dotfiles/desktop/.emacs.d/snippets/sh-mode/fnae

@@ -0,0 +1,7 @@
+assertEquals() {
+  test "\$1" = "\$2" || {
+    printf "Failed: Expected: [%s] Actual: [%s]\\n" "\${1}" "\${2}"
+    exit 1
+  }
+}
+$0