Bootstrap extension example

Would be nice to have an example showing how to e.g. project shared state from a bootstrap extension into worker thread local variables, used by HTTP/etc extensions running in workers. I have bootstrap HTTP callouts as the source of this state in mind, but they aren't released in 1.37, I don't think?

在此仓库中找到 bootstrap 扩展和 worker-thread HTTP 扩展的示例，然后跟踪共享状态如何移动到 worker thread 局部变量中。确认 bootstrap HTTP callout 是否在 Envoy 1.37 之后仍可用；完成的标准是有一个可运行的示例展示 HTTP 或其他 worker 扩展的状态流转。

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