Add a perf-based benchmark

[nbraud]

First step towards #90. Depends on #91

[nbraud]

Is there anything that needs to be done for this PR to be mergeable?

[AstraLuma]

I guess my only question is, how should this be used?

[nbraud]

@astronouth7303 I don't think this needs to be a full solution to #90 ?
Just having the ability to benchmark and compare is pretty useful, since it means we can easily check what's the performance impact of any given change (rather than me inventing a microbenchmark).

Moreover, the maintenance cost is negligible, since it's a script with less than 20 lines, which nothing depends on, and which doesn't need updating when adding new functions in Vector2 (thanks to tests.utils.*_OPS).