Add 'define-error' to font lock keywords for emacs-lisp-mode

* lisp/emacs-lisp/lisp-mode.el (lisp-fdefs): Add 'define-error'.
(Bug#64824)

* test/lisp/emacs-lisp/lisp-mode-tests.el
(test-font-lock-keywords): New test.

Copyright-paperwork-exempt: yes

lisp/emacs-lisp/lisp-mode.el

@@ -361,7 +361,7 @@ This will generate compile-time constants from BINDINGS."
                  "define-globalized-minor-mode" "define-skeleton"
                  "define-widget" "ert-deftest"))
      (el-vdefs '("defconst" "defcustom" "defvaralias" "defvar-local"
-                 "defface"))
+                 "defface" "define-error"))
      (el-tdefs '("defgroup" "deftheme"))
      (el-errs '("user-error"))
      ;; Common-Lisp constructs supported by EIEIO.  FIXME: namespace.