refactor(output): share the JSON, created-resource and batch tails

Mutations end with a.jsonResult or a.created instead of hand-rolled
--json branches, the two identical jsonResult/writeMutationJSON helpers
become one, and writeBatchJSON checks --json itself so batch commands
share one tail.

Signed-off-by: bircni <bircni@icloud.com>

internal/app/action_runs.go

@@ -617,11 +617,8 @@ $ tea run cancel 34 --force`,
 			if err != nil {
 				return err
 			}
-			if a.options.json != "" {
-				return a.writeJSON(cmd, run)
-			}
 			a.done(cmd, "Requested cancellation of run %d", id)
-			return nil
+			return a.jsonResult(cmd, run)
 		},
 	}
 	cmd.Flags().BoolVar(&force, "force", false, "Cancel without waiting for the runner to acknowledge")
@@ -678,11 +675,8 @@ $ tea run rerun 34 --job build`,
 			if run, err = service.Run(cmd.Context(), id); err != nil {
 				return err
 			}
-			if a.options.json != "" {
-				return a.writeJSON(cmd, run)
-			}
 			a.done(cmd, "Requested rerun of run %d (attempt %d); watch it with: tea run watch %d%s", id, run.Attempt, id, a.suggestedRepo(t))
-			return nil
+			return a.jsonResult(cmd, run)
 		},
 	}
 	cmd.Flags().BoolVar(&failed, "failed", false, "Rerun only the failed jobs")