[flang] Lower elemental calls

[flang] Lower elemental calls

This patch adds more lowering of operations sub-expression inside elemental call arguments.
It tests array contexts where an address is needed for each element (for
the argument), but part of the array sub-expression must be lowered by value
(for the operation)

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

Reviewed By: PeteSteinfeld

Differential Revision: https://reviews.llvm.org/D121606

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