Port benches from reliability branch to v2.0

[expede]

As expected, they look about like what v1.x looked like before the perf improvements

Offline ingest — init({ online:false }),  512 B/file,  fanout 20
┌───────┬─────────┬────────┬─────────┬───────────┬────────┬──────────┬──────────┐
│ Files │ Content │ gen ms │ sync ms │ max block │ blocks │ blocked% │ peak RSS │
├───────┼─────────┼────────┼─────────┼───────────┼────────┼──────────┼──────────┤
│   500 │ text    │     43 │    1729 │    551 ms │      3 │     16 % │   248 MB │
│  1000 │ text    │     74 │    4462 │   1251 ms │      4 │     29 % │   342 MB │
│  2000 │ text    │    158 │   13303 │   2813 ms │      6 │     35 % │   457 MB │
│  4000 │ text    │    414 │   60527 │  13234 ms │      6 │     26 % │   722 MB │
└───────┴─────────┴────────┴─────────┴───────────┴────────┴──────────┴──────────┘

Changes ported from reliability begin with #39