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.
Because dired+ must be loaded before the dired creates a buffer, we have
to actually manually require dired+ when loading dired. Otherwise the
first dired buffer within a fresh Emacs instance will have dired+
features, but any further buffers will.
Also we can now remove a workaround for dired+ with Emacs 28 that
prevented files/folders from being deleted with dired.