Geometry `nearest` functions should take generic collection

[rzblue]

In java, nearest currently takes a List<T> but could take Collection<T> with no implementation changes. In C++ we currently take std::span but could take iterators.

[calcmogul]

Taking an iterator pair directly is frowned upon in modern C++ algorithms, and it would be an API-breaking change. std::span<const Pose2d> or the following are preferred instead.

  template <typename R>
    requires std::ranges::forward_range<R> &&
             std::same_as<std::ranges::range_value_t<R>, Pose2d>
  constexpr Pose2d Nearest(const R&& poses) const {