[llvm] [ORC] Add WaitingOnGraph record / replay facility and test tool. (PR #185275)

[Lang Hames via llvm-commits]

lhames wrote:

@dwblaikie Tagged you for a style question: `llvm-orc-WaitingOnGraph-replay`* is a standalone tool in this commit, but it could alternatively be an option in `llvm-jitlink`. We'd be kind of shoehorning it in there: it's not actually linker related. On the other hand having such a niche top-level tool feels odd. 

* `llvm-orc-WaitingOnGraph-replay` lets us capture and reproduce JIT perf regressions involving `WaitingOnGraph` (e.g. https://github.com/llvm/llvm-project/issues/179611), which should help with diagnosis, profiling, and building a performance regression test suite.

https://github.com/llvm/llvm-project/pull/185275