[VAULT-39150]actions(copy-pr): add step summary to copy PR workflow (#9828) (#9930)

When we copy a Pull Request from CE to Ent we already add a status
comment to the origin PR but we don't actually bubble up the information
to the workflow summary. Instead, render the copy PR output as a
markdown table and write it to the step summary.

Signed-off-by: Ryan Cragun <me@ryan.ec>
Co-authored-by: Ryan Cragun <me@ryan.ec>

tools/pipeline/internal/cmd/github_copy_pull_request.go

@@ -67,6 +67,10 @@ func runCopyGithubPullRequestCmd(cmd *cobra.Command, args []string) error {
 			return errors.Join(err, err1)
 		}
 		fmt.Println(string(b))
+	case "markdown":
+		tbl := res.ToTable(err)
+		tbl.SetTitle("Copy Pull Request")
+		fmt.Println(tbl.RenderMarkdown())
 	default:
 		fmt.Println(res.ToTable(err).Render())
 	}