Implement LazyRelativeSignal for lazy evaluation

[timonkrebs]

Something like this: https://github.com/timonkrebs/MemoizR/commit/c17aafe8ab95a5f9bcb1c8e768fea1c6e858b287

with ConcurrentQueue: https://learn.microsoft.com/en-us/dotnet/api/system.collections.concurrent.concurrentqueue-1?view=net-7.0