GSoC 2022: Thin SDK for Proxy Mesh

Please read the [detailed proposal of Dubbo Proxy Mesh](https://github.com/apache/dubbo-awesome/blob/master/proposals/D3.1-thinsdk-sidecar-mesh.md) here first to know about the ultimate goal behind this issue.

We have started the development of Dubbo Proxy Mesh for a while, so that means you don't have to start the project from the scratch, anyone who gets involved needs to start with a specific task at hand. As for the specific tasks to do in GSoC 2022, we are still working on it, we do have some tasks that can be distributed but we hope to discuss them with the contributors first.

So if you are interested in this project and the objective described in the proposal, please leave comments below so we can further exchange opinions.

Please don't forget to apply for GSoC from its official website when the application slot opens.

Start by reading proposals/D3.1-thinsdk-sidecar-mesh.md to understand the proposed Dubbo Proxy Mesh goal. The issue does not name an implementation entry point, specific task, test, or completion condition; review the existing development and comment discussion before choosing a scoped task.

Written by the indexing model from the issue text.