Hybrid cache performance

[MarkCiliaVincenti]

This PR replaces the locking mechanism with the battle-tested AsyncKeyedLock library (disclaimer: I am the author of this library).

The locking mechanism here reduces allocations (due to pooling of objects) and avoids the existing double-check of the dictionary (which is technically a race condition because if the reference matches inside the finally, there is no guarantee that by the time it's removed that another thread hasn't obtained the lock).

[github-actions]

Hi there @MarkCiliaVincenti, thank you for this contribution! 👍

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[Zeegaan]

Hello there, first of all, thank you for the effort on creating this 💪
Sadly, the team sentiment is that we do not want to add another dependency for this, as we don't think it is worth it in this case.
I will go ahead and close this, once again thank you for taking the time here even though we aren't merging this 🙏