lints workflow : feature or crate selection

Documenting an issue encountered in https://github.com/lurk-lab/neptune/pull/255, which is arguably the fault of the crate organization:
- the gbench crate (which is non-publish!) runs with the default opencl feature, which does not compile on some CI machines:
https://github.com/lurk-lab/neptune/blob/main/gbench/Cargo.toml#L25
- the lint crate runs with `workspace` in the doc step of the job:
https://github.com/lurk-lab/neptune/actions/runs/7294189991/job/19878612122?pr=255
https://github.com/lurk-lab/ci-workflows/blob/96e567fa741858807c1de28bb4d8194291faecfb/.github/workflows/lints.yml#L49

Three ways to solve this:
- make the gbench feature non-default, just generate a runtime panic if neither of opencl nor cuda are active,
- allow excluding a crate from the doc test,
- allow excluding a feature (or running with default-deatures = false) from the doc test,

Start by reading .github/workflows/lints.yml in ci-workflows, the gbench/Cargo.toml feature definition, and the referenced PR #255. Compare how the doc step invokes the lint crate and determine which crate or feature-selection behavior should be supported. Done means the workflow can handle the documented crate and feature-selection cases without failing on unsupported default features.

Written by the indexing model from the issue text.