Reland [flang] Generalized simplification of HLFIR reduction ops. (llvm#136071) (llvm#136246)

This change generalizes SumAsElemental inlining in
SimplifyHLFIRIntrinsics pass so that it can be applied
to ALL, ANY, COUNT, MAXLOC, MAXVAL, MINLOC, MINVAL, SUM.

This change makes the special handling of the reduction
operations in OptimizedBufferization redundant: once HLFIR
operations are inlined, the hlfir.elemental inlining should
do the rest of the job.

Author: vzakhari