[llvm] [Offload] Move RPC server handling to a dedicated thread (PR #112988)

[Shilei Tian via llvm-commits]

https://github.com/shiltian approved this pull request.

LGTM but I'd defer the initialization of RPC stuff to the first kernel that uses it instead of at initialization stage. In the worst case, it can have a kernel that depends on RPC but doesn't actually launch it.

https://github.com/llvm/llvm-project/pull/112988