ci(bench): allow dispatch benchmarks with cargo features

[Rjected]

Adds an optional cargo_features input to the existing workflow_dispatch trigger for the CodSpeed benchmark workflow.

Manual runs can now pass package-qualified Cargo feature strings such as revm-precompile/gmp to the CodSpeed build step. When the input is empty, the workflow executes the same cargo codspeed build --profile profiling --workspace --exclude '*example*' command as before. The cargo codspeed run --workspace invocation is unchanged, so automatic pull_request and push behavior remains unchanged.

Validation: git diff --check. actionlint is not installed in this environment.

[codspeed-hq]

Merging this PR will not alter performance

✅ 181 untouched benchmarks
⏩ 1 skipped benchmark¹

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_{Comparing dan/bench-dispatch-cargo-features (dea9f69) with main (84fe60c)}

Footnotes

1. 1 benchmark was skipped, so the baseline result was used instead. If it was deleted from the codebase, click here and archive it to remove it from the performance reports. ↩