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/java-mode/req

@@ -0,0 +1,6 @@
+#name : req
+# --
+HttpRequest request = HttpRequest.newBuilder()
+  .uri(URI.create($0))
+  .timeout(Duration.ofMillis(getResponseTimeout()))
+  .build();