`IntoValueIterator`

[arcnmx]

Due to the need to reset an iterator prior to iterating, it feels like there needs to be two layers of typed iterators:

• [x] IntoValueIterator<T>: a thin wrapper around a WpIterator (new name subject to change/suggestions)
  • [x] all iterator bindings should return this instead of ValueIterator<T>
  • [x] hide all bindings returning an untyped WpIterator behind pub(crate) (or just manually implement them and mark ignore=true in gir)
  • [x] consumer can into_inner() this to get the untouched FFI value if desired
  • [x] impls IntoIterator<IntoIter = ValueIterator<T>>
  • [x] self.reset() before returning the new iterator, assuming the referenced bug still exists
  • [ ] remove new_ prefix from any new_x_iterator methods
• [x] ValueIterator<T>: a wrapper around a WpIterator that casts the values to the specified type
  • [x] impls Iterator<Item = T>
  • [x] this could use a .upcast() -> ValueIterator<U> where U: IsA<T>