fixes#17163, refs #23204
Types that aren't `tyRange` and are bigger than 16 bits, so `int32`,
`uint64`, `int` etc, are disallowed as array index range types.
`tyRange` is excluded because the max array size is backend independent
(except for the specific size of `high(uint64)` which crashes the
compiler) and so there should still be an escape hatch for people who
want bigger arrays.
