New function substitute-quotes

New function substitute-quotes

* lisp/help.el (substitute-quotes): New function.  (Bug#51040)
* doc/lispref/help.texi (Keys in Documentation): Document
substitute-quotes.
* test/lisp/help-tests.el (help-tests-substitute-quotes): New test.

* lisp/cedet/srecode/srt-mode.el (srecode-macro-help):
* lisp/cus-theme.el (describe-theme-1):
* lisp/emacs-lisp/cl-extra.el (cl--describe-class):
* lisp/emacs-lisp/eieio-opt.el (eieio-help-constructor):
* lisp/emacs-lisp/package.el (describe-package-1):
* lisp/help-fns.el (help-fns--parent-mode, help-fns--var-risky)
(help-fns--var-file-local, help-fns--var-bufferlocal)
(describe-face):
* lisp/help.el (substitute-command-keys):
* lisp/progmodes/octave.el (octave-help): Use the new function
instead of 'substitute-command-keys'.