[Draft] stdc++ current working version

[rasky]

This PR shows my local branch where I'm progressing in migration to stdc++ containers. It is not meant for review/merging, but just to glimpse at my current state and maybe discuss of changes before they end into PRs.

The following containers/classes are completely removed in this branch (checked if the full migration has already been merged to master):

• nall::vector => std::vector
• nall::array_view / nall::array_span => std::span
• nall::merge_sort => std::stable_sort
• nall::function => std::function
• nall::unique_pointer => std::unique_ptr
• nall::shared_pointer => std::shared_ptr
• nall::hashset => std::unordered_map
• nall::map => std::map
• nall::set => std::set
• nall::array => std::array