make graph data lazy for reused binary lists

[cornmander]

fixes #3128.

summary

This change delays loading the Cargo package graph until it is actually needed, instead of constructing it in BaseApp::new unconditionally.

For cargo nextest list --list-type binaries-only with reused --binaries-metadata, that means nextest can skip cargo metadata and the PackageGraph in the common fast path, resolve the workspace root with cargo locate-project, and still preserve the existing diagnostics for CLI filter parsing.

The normal non-reused list path is not materially changed by this patch.

performance

Benchmarks were run with warm caches on macOS (aarch64-apple-darwin) using hyperfine, comparing origin/main with this branch.

• tokio (e67cd87, 264 binaries): 121.6 ms ± 2.3 ms -> 52.8 ms ± 0.8 ms for nextest list --list-type binaries-only --binaries-metadata ... --message-format json.
• tokio: 2.30x faster, or about 56.5% lower wall time.
• rust-analyzer (51966da, 68 binaries): 174.7 ms ± 9.6 ms -> 57.3 ms ± 1.5 ms for the same command.
• rust-analyzer: 3.05x faster, or about 67.2% lower wall time.

The avoided Cargo startup cost lines up with the improvement:

• tokio: cargo metadata --format-version=1 --all-features --filter-platform aarch64-apple-darwin was 87.2 ms ± 3.5 ms, while cargo locate-project --workspace --message-format plain was 39.6 ms ± 0.7 ms.
• rust-analyzer: the same commands were 122.5 ms ± 5.7 ms and 45.5 ms ± 2.4 ms.

testing

• cargo xfmt --check
• cargo check -p cargo-nextest -p integration-tests
• cargo nextest run -p cargo-nextest
• cargo nextest run -p integration-tests -E 'test(test_list_binaries_only) or test(test_list_binaries_only_after_build) or test(test_list_full_after_build) or test(test_list_host_after_build) or test(test_list_target_after_build)'

[codecov]

Codecov Report

❌ Patch coverage is 0% with 226 lines in your changes missing coverage. Please review.
✅ Project coverage is 0.88%. Comparing base (9531cb9) to head (9575ed0).
⚠️ Report is 90 commits behind head on main.

Files with missing lines	Patch %	Lines
cargo-nextest/src/dispatch/core/base.rs	0.00%	123 Missing ⚠️
cargo-nextest/src/dispatch/core/list.rs	0.00%	59 Missing ⚠️
cargo-nextest/src/dispatch/helpers.rs	0.00%	31 Missing ⚠️
cargo-nextest/src/dispatch/core/run.rs	0.00%	9 Missing ⚠️
cargo-nextest/src/dispatch/core/archive.rs	0.00%	4 Missing ⚠️

❗ There is a different number of reports uploaded between BASE (9531cb9) and HEAD (9575ed0). Click for more details.

HEAD has 1 upload less than BASE

Flag	BASE (9531cb9)	HEAD (9575ed0)
	2	1

Additional details and impacted files

@@            Coverage Diff             @@
##             main   #3132       +/-   ##
==========================================
- Coverage   84.43%   0.88%   -83.55%     
==========================================
  Files         156     152        -4     
  Lines       42733   42009      -724     
==========================================
- Hits        36080     371    -35709     
- Misses       6653   41638    +34985     

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