Add benchmark(s) for interpolation

[trexfeathers]

📰 Custom Issue

We don't have any currently. There are plenty of existing benchmarks that could be used as inspiration (e.g. regridding.py, trajectory.py).

At the very least this should demonstrate the performance improvements described here: #6084 (comment). I didn't want to hold up that pull request any more, so didn't ask for a benchmark as part of that work.