opp-repl-github-actions

Dispatch GitHub Actions CI workflows from opp_repl. Requires `github` extra, a personal access token at ~/.ssh/github_repo_token (repo + workflow scopes), and github_owner/github_repository/github_workflows parameters in the project's .opp file. dispatch_workflow and dispatch_all_workflows fire workflow_dispatch events; combine with `opp-repl-fingerprint-tests` etc. locally.