fix!: use the git CLI for action clones and make builtin:checkout match actions/checkout (#1277)

The runner now uses the `git` command line instead of go-git to download actions and reusable workflows. go-git had recurring bugs and does not support SHA-256 repositories, and full clones of actions are several times faster.

`builtin:checkout` now runs `git` where the job runs and behaves like `actions/checkout`:

1. A branch is checked out as a local branch tracking `origin`, tag and pull request runs keep their ref, and a triggering tag that moved fails the step.
1. Later steps can fetch and push with the persisted token or SSH key.
1. It supports the `ssh-*`, `lfs`, `submodules`, `sparse-checkout`, `filter`, `fetch-tags`, `clean`, `persist-credentials`, `show-progress` and `set-safe-directory` inputs and the `ref` and `commit` outputs.
1. SHA-256 repositories work for actions, reusable workflows and `builtin:checkout`.

Git keeps the token off its command line, ignores `GIT_DIR` and similar variables inherited by the runner, and keeps action files LF regardless of `core.autocrlf`. A cancelled job lets git remove its lock files.

This is a breaking change: the runner needs Git 2.34.1 or newer on its `PATH`, and so do job images that use `builtin:checkout`. The official runner images include it.

Fixes: https://gitea.com/gitea/runner/issues/1077
Fixes: https://gitea.com/gitea/runner/issues/1267
Fixes: https://gitea.com/gitea/runner/issues/1279
Fixes: https://gitea.com/gitea/runner/issues/1284
Fixes: https://gitea.com/gitea/runner/issues/1285
Co-authored-by: silverwind <[email protected]>
Co-authored-by: silverwind <[email protected]>
Co-authored-by: Lunny Xiao <[email protected]>
Reviewed-on: https://gitea.com/gitea/runner/pulls/1277
Reviewed-by: Lunny Xiao <[email protected]>
Reviewed-by: silverwind <[email protected]>
Co-authored-by: bircni <[email protected]>

e2e/gitea_api.go

@@ -53,6 +53,12 @@ func (a *GiteaAPI) CreateFile(ctx context.Context, repo, path, content, message
 	return a.doJSON(ctx, http.MethodPost, url, body, nil)
 }
 
+func (a *GiteaAPI) CreateTag(ctx context.Context, repo, name string) error {
+	body := map[string]any{"tag_name": name}
+	url := fmt.Sprintf("/api/v1/repos/%s/%s/tags", giteaAdminUser, repo)
+	return a.doJSON(ctx, http.MethodPost, url, body, nil)
+}
+
 func (a *GiteaAPI) CreateSecret(ctx context.Context, repo, name, value string) error {
 	body := map[string]any{"data": value}
 	url := fmt.Sprintf("/api/v1/repos/%s/%s/actions/secrets/%s", giteaAdminUser, repo, name)