Add prototool format

clang-format is pretty limited in its formatting options of *.proto, prototool is much more complete

**Describe the solution you'd like**
Add the prototool (https://github.com/uber/prototool) formatter as an option

**Describe alternatives you've considered**
Have not tried any alternatives, I don't believe there is an alternative?

issue 中没有指定文件或测试。首先跟踪现有的 clang-format 集成以及 formatter 选项的注册方式，然后确定应在何处为 *.proto 文件添加 prototool。新的 formatter 选项可用，并且能够通过 plugin 格式化 protobuf 文件，即表示完成。

由索引模型根据 Issue 内容生成。