fix(dired+): dired operations with multiple selected files work again

There was recently a great tidy-up commit in the Emacs master
branch (commit 1f29ee2d21b57e81a28550a1b31bc8a39406d17b), which removed
a lot legacy stuff. Dired's dired-pop-to-buffer function was among them.

However dired+ plus seems to heavily depend on it, so for now, I've
simply copied the source of the function from the legacy cleanup commit.

modules/navigation/siren-dired+.el

@@ -22,7 +22,33 @@
   :config
   (unbind-key "M-b" dired-mode-map)
   (unbind-key "M-i" dired-mode-map)
-  (unbind-key "M-l" dired-mode-map))
+  (unbind-key "M-l" dired-mode-map)
+
+  (when (not (fboundp 'dired-pop-to-buffer))
+    ;; Emacs 29.x has removed the legacy dired-pop-to-buffer function from dired
+    ;; in commit 1f29ee2d21b57e81a28550a1b31bc8a39406d17b.
+    ;;
+    ;; Dired+ depends heavily on dired-pop-to-buffer, so here we re-define the
+    ;; version that was removed from Emacs.
+    (defun dired-pop-to-buffer (buf)
+      "Pop up buffer BUF in a way suitable for Dired."
+      (declare (obsolete pop-to-buffer "24.3"))
+      (let ((split-window-preferred-function
+             (lambda (window)
+               (or (and (let ((split-height-threshold 0))
+                          (window-splittable-p (selected-window)))
+                        ;; Try to split the selected window vertically if
+                        ;; that's possible.  (Bug#1806)
+                        (split-window-below))
+                   ;; Otherwise, try to split WINDOW sensibly.
+                   (split-window-sensibly window))))
+            pop-up-frames)
+        (pop-to-buffer (get-buffer-create buf)))
+      ;; See Bug#12281.
+      (set-window-start nil (point-min))
+      ;; Try to not delete window when we want to display less than
+      ;; `window-min-height' lines.
+      (fit-window-to-buffer (get-buffer-window buf) nil 1 nil nil t))))
 
 (provide 'siren-dired+)
 ;;; siren-dired+.el ends here