Optimize with specialized function

Outlook pretty good for the perf boosts - lowest in the set is 11x,
things with nested coordinates are reliably 80x faster. Intent here is
to speed up these functions so that we can very quickly precalculate
extents to cheat at big point-in-polygon tests.

turf-extent#FeatureCollection x 68,811 ops/sec ±3.18% (91 runs sampled)
turf-extent2#FeatureCollection x 5,900,717 ops/sec ±0.74% (95 runs sampled)
turf-extent#Point x 1,897,230 ops/sec ±0.62% (100 runs sampled)
turf-extent2#Point x 23,233,254 ops/sec ±0.99% (87 runs sampled)
turf-extent#LineString x 1,069,412 ops/sec ±1.13% (94 runs sampled)
turf-extent2#LineString x 11,069,338 ops/sec ±0.79% (94 runs sampled)
turf-extent#Polygon x 101,199 ops/sec ±1.42% (95 runs sampled)
turf-extent2#Polygon x 8,811,913 ops/sec ±0.66% (98 runs sampled)
turf-extent#MultiLineString x 98,191 ops/sec ±0.69% (99 runs sampled)
turf-extent2#MultiLineString x 6,838,203 ops/sec ±0.57% (95 runs sampled)
turf-extent#MultiPolygon x 29,325 ops/sec ±0.79% (98 runs sampled)
turf-extent2#MultiPolygon x 6,317,757 ops/sec ±0.56% (94 runs sampled)