[flang][runtime] Handle incomplete NAMELIST input derived type compon… (#66831)

…ent list

When a derived type value appears in NAMELIST input, its components'
values appear in sequence. This sequence can be truncated by a NAME=
that begins the next NAMELIST input item, or by the terminal '/' that
ends the NAMELIST group. Extend the mechanism already in place for
truncated array item lists in NAMELIST input so that it also applies to
derived type component sequences, and rename things appropriately.