[flang][OpenMP] Improve locality check when determining DSA (#180583)

Follow-up to https://github.com/llvm/llvm-project/pull/178739.

The locality check assumed that immediately after the initial symbol
resolution (i.e. prior to the OpenMP code in resolve-directives.cpp),
the scope that owns a given symbol is the scope which owns the symbol's
storage. Turns out that this isn't necessarily true as illustrated by
the included testcase, roughly something like:
```
program main
  integer :: j        ! host j (storage-owning)
  contains
  subroutine f
    !$omp parallel    ! scope that owns j, but j is host-associated
    do j = ...
    end do
    !$omp end parallel
  end
end program
```

In such cases, the locality should be checked for the symbol that owns
storage, i.e. a clone of the symbol that is has been privatized or a
symbol that is not host- or use-associated. This is similar to obtaning
the ultimate symbol (i.e. from the end of association chain), except the
chain traversal would stop at a privatized symbol, potentially before
reaching the end.

This fixes a few regressions in the Fujitsu test suite:
Fujitsu/Fortran/0160/Fujitsu-Fortran-0160_0000.test
Fujitsu/Fortran/0160/Fujitsu-Fortran-0160_0012.test
Fujitsu/Fortran/0160/Fujitsu-Fortran-0160_0013.test
Fujitsu/Fortran/0660/Fujitsu-Fortran-0660_0096.test
Fujitsu/Fortran/0660/Fujitsu-Fortran-0660_0097.test
Fujitsu/Fortran/1052/Fujitsu-Fortran-1052_0108.test
Fujitsu/Fortran/1052/Fujitsu-Fortran-1052_0112.test