[flang] Change two member functions of DerivedTypeDetails to non-member

In `OrderParameterNames` and `OrderParameterDeclarations` it was
always true that `this == &type.get<DerivedTypeDetails>()` which
meant that `this` was redundant.

So convert them to non-member functions in `tools.h` that get the
details from the symbol passed in. This makes life simpler for the
callers.

Original-commit: flang-compiler/f18@81710d4e6ec9e316d95b955a1efd253d9c485fef
Reviewed-on: https://github.com/flang-compiler/f18/pull/559