* lisp/subr.el (method-files): Move function to cl-generic.el

* lisp/subr.el (method-files): Move function to cl-generic.el

* lisp/emacs-lisp/cl-generic.el (cl-generic-p): New function.
(cl--generic-method-files): New function, moved from subr.el.
* lisp/emacs-lisp/edebug.el (edebug-instrument-function): Use them.
* test/lisp/emacs-lisp/cl-generic-tests.el:
* test/lisp/subr-tests.el: Move and adjust method-files tests accordingly.