Support more functions with plugins

[aa51513]

As we all know, an excellent software will meet many mainstream needs.

Handing over the implementation of some features to other software will force users to glue the software, which will cause two problems:

1. More system resource consumption (one more process needs to be opened), higher network delay (if reverse proxy is used);
2. Worse overall stability (third-party software stability is unknown);

I don't mean to let rathole support every need of everyone, but the mainstream needs still need to be supported

What is your opinion on this?