feat: generate config docs on ci

[Jiloc]

Description

Adds node-config-docsgen to the CI workflow to automatically create an artifact of the node documentation.
It also slightly modify contrib/tools/config-docs-generator/generate-config-docs.sh to have a configurable output used by the action.

In draft till the corresponding action PR will be merged stacks-network/actions#77

Applicable issues

• last step of Document config.toml options automatically #5898

Additional info (benefits, drawbacks, caveats)

Checklist

• Test coverage for new or modified code paths
• Changelog is updated
• Required documentation changes (e.g., docs/rpc/openapi.yaml and rpc-endpoints.md for v2 endpoints, event-dispatcher.md for new events)
• New clarity functions have corresponding PR in clarity-benchmarking repo
• New integration test(s) added to bitcoin-tests.yml