Edit audiences with the SDK

Hi, we are using Optimizely in our organization and now there is a requirement for updating audiences, we searched a lot, and apparently, there is no such feature in the java SDK.

The requirement is that there is a micro-service that notifies us to include a new audience in an already existing feature flag (we want to roll out a feature in our backends by cities) and we need to add the new audience programmatically to the audiences whenever the other micro-service tell us. This is not an A/B test or an experiment it is actually a rollout plan.

首先审查用于 feature flags 和 audiences 的 Java SDK APIs；该 issue 未指定文件、测试或入口点。确定是否支持以编程方式更新 audiences，并定义将 audience 添加到现有 rollout 所需的 API 行为，包括如何验证完成情况。