refactor: use a function to export table apis.

* specs/table_spec.yaml (clone, clone_select, elems, empty)
(ielems, invert, keys, merge, merge_select, metamethod)
(monkey_patch, new, pack, ripairs, size, totable, values):
Update to latest style:
Add "too many argument" behaviour checks.
Simplify and standardise argument error message comparisons.
* lib/std/table.lua (M): Add module name at element 1.
(clone, clone_select, elems, empty, ielems, invert, keys)
(merge, merge_select, metamethod, monkey_patch, new, pack)
(ripairs, size, totable, values): Upgrade to base export
declarations (for overhead free argcheck calls with _DEBUG=false)
and simplify accordingly.

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