Reduce overhead in converting resolutions (#11660)
Solving spent a chunk of its time just converting resolutions, the left
two blocks:
These blocks are `ResolverOutput::from_state` with 1.3% and
`ForkState::into_resolution` with 4.1% of resolver thread runtime for
apache airflow universal.
We reduce the overhead spent in those functions, to now 1.1% and 2.1% of
resolver time spend in those functions by:
Commit 1: Replace the hash set for the edges with a vec in
`ForkState::into_resolution`. We deduplicate edges anyway when
collecting them, and the hash-and-insert was slow.
Commit 2: Reduce the distribution clonign in
`ResolverOutput::from_state` by using an `Arc`.
The same profile excerpt for the resolver with the branch (note that
there is now an unrelated block between the two we optimized):
Wall times are noisy, but the profiles show those changes as
improvements.
```
$ hyperfine --warmup 2 "./uv-main pip compile --no-progress scripts/requirements/airflow.in --universal" "./uv-branch pip compile --no-progress scripts/requirements/airflow.in --universal"
Benchmark 1: ./uv-main pip compile --no-progress scripts/requirements/airflow.in --universal
Time (mean ± σ): 99.1 ms ± 3.8 ms [User: 111.8 ms, System: 115.5 ms]
Range (min … max): 93.6 ms … 110.4 ms 29 runs
Benchmark 2: ./uv-branch pip compile --no-progress scripts/requirements/airflow.in --universal
Time (mean ± σ): 97.1 ms ± 4.3 ms [User: 114.8 ms, System: 112.0 ms]
Range (min … max): 90.9 ms … 112.4 ms 29 runs
Summary
./uv-branch pip compile --no-progress scripts/requirements/airflow.in --universal ran
1.02 ± 0.06 times faster than ./uv-main pip compile --no-progress scripts/requirements/airflow.in --universal
```
