lang/org: refactor contrib modules

- Fix #1546
- Ensure contrib modules aren't included in byte-compilation/autoload
  generation if their requisite flags aren't enabled

modules/lang/org/autoload/org-attach.el

@@ -98,47 +98,3 @@ the cursor."
                  (org-download-insert-link raw-uri new-path))))
       (error
        (user-error "Failed to attach file: %s" (error-message-string ex))))))
-
-;;;###autoload
-(defun +org-attach-download-dnd (uri action)
-  "TODO"
-  (if (eq major-mode 'org-mode)
-      (+org-attach/uri uri)
-    (let ((dnd-protocol-alist
-           (rassq-delete-all '+org-attach-download-dnd
-                             (copy-alist dnd-protocol-alist))))
-      (dnd-handle-one-url nil action uri))))
-
-
-;;
-;; Advice
-
-;;;###autoload
-(defun +org-attach*insert-link (_link filename)
-  "Produces and inserts a link to FILENAME into the document.
-
-If FILENAME is an image, produce an attach:%s path, otherwise use file:%s (with
-an file icon produced by `+org-attach--icon')."
-  (if (looking-back "^[ \t]+" (line-beginning-position))
-      (delete-region (match-beginning 0) (match-end 0))
-    (newline))
-  (cond ((image-type-from-file-name filename)
-         (insert
-          (concat (if (= org-download-image-html-width 0) ""
-                    (format "#+attr_html: :width %dpx\n" org-download-image-html-width))
-                  (if (= org-download-image-latex-width 0) ""
-                    (format "#+attr_latex: :width %dcm\n" org-download-image-latex-width))
-                  (cond ((file-in-directory-p filename org-attach-directory)
-                         (format "[[attach:%s]]" (file-relative-name filename org-attach-directory)))
-                        ((file-in-directory-p filename org-directory)
-                         (format org-download-link-format (file-relative-name filename org-directory)))
-                        (t
-                         (format org-download-link-format filename)))))
-         (org-display-inline-images))
-        (t
-         (insert
-          (format "%s [[./%s][%s]] "
-                  (+org-attach--icon filename)
-                  (file-relative-name filename (file-name-directory buffer-file-name))
-                  (file-name-nondirectory (directory-file-name filename)))))))
-