add lldb bthread stack debug script

[ehds]

What problem does this PR solve?

Issue Number:

Problem Summary:
新增支持 lldb 的 bthread 堆栈调试工具，使用方法和命令和 gdb 脚本保持一致。

Get Started:

1. lldb attach <pid>
2. command script import lldb_bthread_stack.py
3. bthread_begin
4. bthread_list
5. bthread_frame 0
6. bt / up / down
7. bthread_end

What is changed and the side effects?

Changed:

Side effects:

• Performance effects(性能影响):

• Breaking backward compatibility(向后兼容性):

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Check List:

• Please make sure your changes are compilable(请确保你的更改可以通过编译).
• When providing us with a new feature, it is best to add related tests(如果你向我们增加一个新的功能, 请添加相关测试).
• Please follow Contributor Covenant Code of Conduct.(请遵循贡献者准则).