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/webhooks.go

@@ -431,10 +431,7 @@ $ tea webhook create https://hooks.slack.com/services/T0/B0/X --org acme --type
 			return err
 		}
 		a.done(cmd, "Created %s in %s for %s", webhookLabel(hook), webhookScopeName(service.Scope), collapsedEvents(hook.Events))
-		if err := a.printURL(cmd, webhookSettingsURL(target, service.Scope, hook.ID)); err != nil {
-			return err
-		}
-		return a.jsonResult(cmd, hook)
+		return a.created(cmd, hook, webhookSettingsURL(target, service.Scope, hook.ID))
 	}
 	return command
 }