Add a checkout-repository input to support checking out other repositories #119

Problem

The Checkout Code step in action.yml doesn't pass a repository to actions/checkout, so the action can only check out the repository the workflow is running in. Workflows that need to check out a different repository (e.g. a private repo from an automation repo) can't do it through this action.

Proposal

• Add an optional checkout-repository input (owner/repo), defaulting to ${{ github.repository }} so existing callers see no change.
• Pass it through to actions/checkout as repository.
• The existing checkout-token input already goes to actions/checkout as token. Confirm and document that it can be used with checkout-repository to authenticate to a private repository.
• Update README.md with the new input and a cross-repo checkout example.

Acceptance Criteria

• checkout-repository input added with a backward-compatible default
• Existing callers that don't set the input behave exactly as before
• A job can check out a different (private) repository at a given ref using checkout-repository + checkout-ref + checkout-token
• README updated
• New release published

Related

• hashgraph/hedera-consensus-node#49