chore(dev/benchmarks): Benchmark coordinate sequence iteration

[paleolimbot]

This PR benchmarks coordinate iteration (and fixes the previous benchmarks benchmark the same cases). Some takeaways:

• In C, GEOARROW_COORD_VIEW_VALUE(), which uses i * coord_stride, seems to prevent the compiler from doing some optimization which is possible when incrementing the pointer by coord_stride in each iteration of the loop. However, this only affects bounds calculation and not the centroid calculation.
• In C++, the STL iterator does a slightly better job optimizing i * coord_stride and in one case seems to do slightly better.

This PR also adds "dimension iterators" dbegin() and dend() for iterating over a particular dimension.

My personal takeaway is that except for possibly very cheap operations (like bounding, winding, and centroid calculations), C++ STL iteration is probably fine. A good reason to use dimension-specific iteration is if you are specifically aiming for autovectorization of some kind (or if you specifically are discarding values from another dimension).