Optimize lists

[KCreate]

• Currently each list read / write access has to be synchronized via a lock, as multiple fibers could access it at the same time.
• In a simple stress test (accessing the same offset in an infinite loop), lock and unlock of the objects TinyLock take up ~20% of the entire execution time
• Maybe there is some fancy lock-free data-structure that implements dynamic vectors.
  • Lock-free Dynamically Resizable Arrays, D. Dechev, P. Pirkelbauer, and B. Stroustrup
• Creating lists via List.create will initialize fields to null. Allocation of backing memory can be deferred until a write access to that index happens. Read access to uninitialized list indices can just statically return null. Requires some profiling and a benchmark to see if this makes sense