Make 'permanent' particle vector channels

[dimaleks]

As of now, the extra particle vector channel are not persistent. They are communicated via MPI, but not preserved during the cell-list update. The goal is to make them truly stick:

• Make CellList reorder data of the extra channels
• Non-primary CellList should keep the reordered extra channels
• Views should be aware of the channels store within the non-primary CellList (e.g. for interactions with charge, etc.)
• Permanent channels should be written and read to/from the restart files

[amlucas]

regarding views: seems very specific, leave it as it is for now