Adding allocated memory to Oceananigans' benchmarks

[simone-silvestri]

Should we add another data entry in https://numericalearth.github.io/OceananigansBenchmarks/ that tracks the memory allocations? It probably will not consume any additional resources but will allow us to track if PRs introduce type instabilities in the code

cc @jackdfranklin @giordano @glwagner

[giordano]

Not sure it's worth it, if we have tests for this: we don't expect significant regressions anyway, unless we forget to update the upper bounds.