[llvm] [ORC] Introduce RedirectionManager interface and implementation using JITLink. (PR #66802)

[Lang Hames via llvm-commits]

lhames wrote:

> What are the prospects for this PR? Do we want to land it in some form? I rebased it to mainline and with some minor fixes the test passes. Now that release/18.x has branched, we'd have some time to revisit it and stabilize it. What do you think?

We definitely want to land it, I've just been short on time to review.
 
> One thing I'd like to discuss is how we can separate management of symbols from stubs. We [have an IndirectStubsManager](https://github.com/llvm/llvm-project/blob/release/18.x/llvm/include/llvm/ExecutionEngine/Orc/IndirectionUtils.h#L281) that we use for lazy JITing and it's already [wired up with EPC](https://github.com/llvm/llvm-project/blob/release/18.x/llvm/lib/ExecutionEngine/Orc/EPCIndirectionUtils.cpp#L54) right?
> 
> Can we integrate it in the redirection manager and avoid more stub management?

The aim is for this work to replace the existing `IndirectStubsManager` (we may reuse the name, but want to update the interface).

https://github.com/llvm/llvm-project/pull/66802