Gather variable binding tests in data-tests.el

Gather variable binding tests in data-tests.el

* test/lisp/emacs-lisp/lisp-tests.el (c-e-x, c-e-l):
Move to data-tests.el.
(core-elisp-tests-2-window-configurations): Rename ...
(core-elisp-tests-1-window-configurations): ... to this.
(core-elisp-tests-3-backquote): Rename ...
(core-elisp-tests-2-backquote): ... to this.
(core-elisp-tests-1-defvar-in-let)
(core-elisp-tests-4-toplevel-values): Move and rename ...
* test/src/data-tests.el (binding-test-defvar-in-let)
(binding-test-toplevel-values): ... to these.
(c-e-x, c-e-l): Moved from data-tests.el.

(cherry picked from commit f699b6e4f409c0cc98703a2cea9b243ff8cb570a)