[flang] Add IO lowering test

This patch adds more lowering tests for IO
Test lowering of IO read SIZE control-spec (12.6.2.15)

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

Reviewed By: jeanPerier

Differential Revision: https://reviews.llvm.org/D121920



Co-authored-by: V Donaldson <vdonaldson@nvidia.com>