Side-project from the last two weeks at work: add perf map support to All The Things!

Added it to #wasmtime, so as to have quick call-graph profiling, and in the process of adding it to #samply too, so it'll automatically load perf maps.

Seriously, if you maintain a language runtime that generates code just-in-time, adding perf map support is one of these little effort / high reward tasks for providing user-land profiling 😍