[flang] Handle structure constructors with forward references to PDTs

We were not correctly handling structure constructors that had forward
references to parameterized derived types.  I harvested the code that checks
for forward references that was used during analysis of function call
expressions and called it from there and also called it during the
analysis of structure constructors.

I also added a test that will produce an internal error without this change.

Differential Revision: https://reviews.llvm.org/D101330