[flang][runtime] Handle array components in NAMELIST input

A namelist input item that is a derived type component reference
needs additional processing when the base item or the component
is an array.  When both have rank > 0, the component reference
must of course be subscripted.

(Fixes https://gitlab-master.nvidia.com/fortran/f18-stage/-/issues/999, NAG test t/tz2.)