Add section on magic trace

[cf-natali]

Magic Trace is an amazing tool using Intel PT to render execution traces, see https://github.com/janestreet/magic-trace?tab=readme-ov-file#getting-started

The book mentions that Intel PT has poor support, but this tool definitely closes a huge gap in terms of debugging and profiling, and should be mentioned.

If that sounds good I could have a look at writing a section on it.

[dendibakh]

Hi @cf-natali, yes, I'm absolutely for it. Feel free to suggest a PR.
I've moved a section about Intel PT to appendix mainly because chapter 6 now covers AMD and ARM PMUs, not just Intel's.