[flang] Handle dynamic array lowering

This patch enables dynamic array lowering
and use the funcationality inside some IO tests.

This patch is part of the upstreaming effort from fir-dev branch.

Depends on D120743

Reviewed By: PeteSteinfeld, schweitz

Differential Revision: https://reviews.llvm.org/D120744



Co-authored-by: Eric Schweitz <eschweitz@nvidia.com>
Co-authored-by: Jean Perier <jperier@nvidia.com>
Co-authored-by: V Donaldson <vdonaldson@nvidia.com>