[flang] Catch semantic error with LBOUND/UBOUND (#154184)
The "ARRAY=" argument to these intrinsics cannot be scalar, whether
"DIM=" is present or not. (Allowing the "ARRAY=" argument to be scalar
when "DIM=" is absent would be a conceivable extension returning an
empty result array, like SHAPE() does with extents, but it doesn't seem
useful in a programming language without compilation-time rank
polymorphism apart from assumed-rank dummy arguments, and those are
supported.)
Fixes https://github.com/llvm/llvm-project/issues/154044.
