Use `using Range = std::array<Value, 2>`.

[1uc]

By using an std::array we can removed the differences between RawIndex and Selection::Ranges. It also allows us to read Selection::Ranges from disk directly via the HighFive API.

[1uc]

This PR contains two variants:

• The first one allows pybind11 to pick the Python type which changes type(selection.ranges) from List[Tuple] to List[List] .
• The second one creates the copy manually and creates a List[Tuple] as before.

Note, that the default STL conversion implies a copy. Hence, this is likely the same amount of copies.

[1uc]

Updates of the BBP stack built on BB5 have been prepared and pass CI: https://github.com/BlueBrain/spack/pull/2216

We needed to change:

- ranges.emplace_back(i_begin, i_end);
+ ranges.push_back({i_begin, i_end});