Use direct nanosecond operations in quanta, bring speed back to baseline

[antifuchs]

This uses https://github.com/metrics-rs/quanta/pull/86 to avoid roundtripping nanosecond counts through Duration, which does a bunch of integer math on construction and deconstruction, which we don't even need (unless we exceed the 270 years of governor's useful operational uptime).

In benchmarks, this brings speeds back to the baseline pre-quanta-0.11 (see #175)

[antifuchs]

bors merge

[codecov[bot]]

Codecov Report

Patch coverage: 100.00% and no project coverage change.

Comparison is base (78ad701) 97.69% compared to head (9c24837) 97.69%.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## master #190 +/- ## ======================================= Coverage 97.69% 97.69% ======================================= Files 31 31 Lines 2208 2208 ======================================= Hits 2157 2157 Misses 51 51 ``` | [Impacted Files](https://app.codecov.io/gh/antifuchs/governor/pull/190?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=Andreas+Fuchs) | Coverage Δ | | |---|---|---| | [governor/src/clock/quanta.rs](https://app.codecov.io/gh/antifuchs/governor/pull/190?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=Andreas+Fuchs#diff-Z292ZXJub3Ivc3JjL2Nsb2NrL3F1YW50YS5ycw==) | `98.52% <100.00%> (ø)` | |

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