[flang] Lower pointer component in derived type

This patch lowers pointer component part of derived types to
FIR.

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

Depends on D121383

Reviewed By: PeteSteinfeld, schweitz

Differential Revision: https://reviews.llvm.org/D121384



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