Replace SantaCache

[pmarkowsky]

Now that Santa no longer needs an in-kernel cache implementation, we should replace the current implementation with one that is more full featured and implements LRU semantics.

One potential option is using the oneTBB library's Concurrent Hash Map implementation as a base. And/or finding some LRU implementation built on top of that, such as thread-safe-lru

Steps to Completion

• [ ] Implement a benchmark
• [ ] Write code and tests
• [ ] Ensure SantaCache replacement is as fast as existing implementation