refactor!(lib): remove {doplist!,plist-delete!,doom-plist-delete}

BREAKING CHANGE: With 26.x support dropped, I've dropped:

- doom-plist-delete: use map-delete instead
- plist-delete!: use cl-callf + map-delete instead
- doplist: use (cl-loop for X on PLIST by #'cddr ...) instead

These were removed as part of an ongoing effort to eliminate
redundancies with built-in packages and reduce Doom's overall footprint.

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

@@ -51,7 +51,7 @@ exist, and `org-link' otherwise."
                          (if (file-exists-p file-name)
                              'org-link
                            'error)))
-           (doom-plist-delete plist :requires))))
+           (plist-put plist :requires nil))))
 
 
 ;;