specs: move legacy goto-char tests to specl.

* lib/zemacs/specs/zlisp_move_spec.yaml (goto-char): New
comprehensive specification for goto-char.
* tests/goto-char.el, tests/goto-char.output,
tests/regression/goto-char_large.el,
tests/regression/goto-char_large.output: Remove obsoleted legacy
test cases.

Signed-off-by: Gary V. Vaughan <gary@gnu.org>