Pass max neighbor guess to ArborX

[aprokop]

So far, just the basic implementation. Things that are to be checked:

• Do we ever exceed that capacity?
• Should it also have the code to increase the capacity? In the Verlet list, the max is always checked and increased by 10%.

[streeve]

We should wait to merge this until ECP-CoPA/Cabana#308 is merged. Then we can either wait and implement maxNeighbor in Cabana, or merge this for now and add the automatic increase later.

The 10% is just to try to avoid counting for small fluctuations in max neighbor count - it should be checked and could be improved

[aprokop]

I think the main challenge with ArborX is a lack of a simple way to determine whether buffer optimization succeeded, i.e. did not go through the second pass. The only (I think) current way of determining that is to do the extra cost computation of explicitly computing max using the offset array. While comparatively not expensive, it is still an extra cost we would unnecessarily incur, and moves us further away from the Verlet baseline.