Add tests for several byte-compiler warnings

Add tests for several byte-compiler warnings

* test/lisp/emacs-lisp/bytecomp-tests.el
(bytecomp/warn-autoload-not-on-top-level\.el)
(bytecomp/warn-callargs\.el)
(bytecomp/warn-defcustom-nogroup\.el)
(bytecomp/warn-defcustom-notype\.el)
(bytecomp/warn-defvar-lacks-prefix\.el)
(bytecomp/warn-format\.el)
(bytecomp/warn-lambda-malformed-interactive-spec\.el)
(bytecomp/warn-make-variable-buffer-local\.el)
(bytecomp/warn-redefine-defun-as-macro\.el)
(bytecomp/warn-redefine-defun\.el)
(bytecomp/warn-redefine-macro-as-defun\.el)
(bytecomp/warn-save-excursion\.el)
(bytecomp/warn-variable-let-bind-constant\.el)
(bytecomp/warn-variable-let-bind-nonvariable\.el)
(bytecomp/warn-variable-set-constant\.el)
(bytecomp/warn-variable-set-nonvariable\.el): New tests.
* test/lisp/emacs-lisp/bytecomp-resources/warn-autoload-not-on-top-level.el:
* test/lisp/emacs-lisp/bytecomp-resources/warn-callargs.el:
* test/lisp/emacs-lisp/bytecomp-resources/warn-defcustom-nogroup.el:
* test/lisp/emacs-lisp/bytecomp-resources/warn-defcustom-notype.el:
* test/lisp/emacs-lisp/bytecomp-resources/warn-defvar-lacks-prefix.el:
* test/lisp/emacs-lisp/bytecomp-resources/warn-format.el:
* test/lisp/emacs-lisp/bytecomp-resources/warn-lambda-malformed-interactive-spec.el:
* test/lisp/emacs-lisp/bytecomp-resources/warn-make-variable-buffer-local.el:
* test/lisp/emacs-lisp/bytecomp-resources/warn-redefine-defun-as-macro.el:
* test/lisp/emacs-lisp/bytecomp-resources/warn-redefine-defun.el:
* test/lisp/emacs-lisp/bytecomp-resources/warn-redefine-macro-as-defun.el:
* test/lisp/emacs-lisp/bytecomp-resources/warn-save-excursion.el:
* test/lisp/emacs-lisp/bytecomp-resources/warn-variable-let-bind-constant.el:
* test/lisp/emacs-lisp/bytecomp-resources/warn-variable-let-bind-nonvariable.el:
* test/lisp/emacs-lisp/bytecomp-resources/warn-variable-set-constant.el:
* test/lisp/emacs-lisp/bytecomp-resources/warn-variable-set-nonvariable.el:
* test/lisp/emacs-lisp/bytecomp-tests.el: New files.