jad 增强直接反编译某个 .class 文件的功能

比如在线上查问题时，可能 `.class`文件是用其它工具 dump出来的，比如是 https://github.com/hengyunabc/dumpclass

这时，又要传回到本地才能反编译。可以考虑直接借用arthas里的 jad 来做反编译。

Start by reading Arthas's existing jad command and how a .class file produced by dumpclass could be supplied to it. Done means a dumped .class file can be decompiled directly through Arthas without first copying it to the local machine; the issue does not name specific files or tests.

Written by the indexing model from the issue text.