Add KeyedMutex

[BalmungSan]

Extention to the current Mutex class to support one look per key.

I extracted the LockQueue and lock implementations into their own file to allow reuse.

I added a basic suite of tests, mostly focused on multiple key interactions.
Since each key is, in essence, its own Mutex I don't think we need to replicate all the complex Mutex tests... since those are actually tests for the LockQueue.

[iRevive]

Should we use a MapRef instead of a Ref[Map]? Could that help reduce contention?

I have observed lower memory footprint while using MapRef instead of Ref[F, Map[K, V]] in some cases.

[armanbilge]

I have observed lower memory footprint while using MapRef instead of Ref[F, Map[K, V]] in some cases.

@iRevive One of the implementations of MapRef is literally a Ref[Map], maybe your observations are related to a ConcurrentHashMap-backed MapRef ?

[iRevive]

I have observed lower memory footprint while using MapRef instead of Ref[F, Map[K, V]] in some cases.

@iRevive One of the implementations of MapRef is literally a Ref[Map], maybe your observations are related to a ConcurrentHashMap-backed MapRef ?

Yes, it was the MapRaf that uses ConcurrentHashMap under the hood.