zlc: support `(interactive "Nprompt: ")`.

Minimum working implementation for integer parameters in
interactive subr declarations.
* lib/zemacs/zlc: Add an integerp function definition to the
preamble of a generated file.
(defsubr): Add code for type checking and argument fetching when
`(interactive "Nprompt: ")` is encountered.
* lib/zemacs/zlisp/move.zl (goto-char): Use `(interactive "N")`
and remove manual argument fetching code.
* lib/zemacs/specs/zlisp_move_spec.yaml (goto-char): Remove
pending markers from argument checking examples.

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