Implementation tooling visibility

[sirdeggen]

From @shruggr, with paraphrasing:

In the existing tooling, hiding of implementation tooling behind internal/private visibility makes it hard to do simple extending of functionality without re-implementing much of the stack. Utilities should all be public to encourage adoption of the base tooling.

[ty-everett]

Completed in PR #320. The repository now exposes the supported implementation, dependency, security, release, and generated-documentation tooling in checked-in developer documentation, and the 95-page docs build/link validation passes in CI.