Provide number of slots to ImMapArray via struct type argument

[dadhi]

• Config settings should be jitted as constants without performance overhead
• Don't take space in ImMapArray to store the config

struct ImMapArray<V, Config> where Config : struct, IImArrayMapSlotConfig 
{
    public bool TryFind(int key, out V value) =>
        Slots[key & default(Config).SlotMask].TryFind(key & default(Config).KeyMask, out value); 
}

struct DefaultConfig : IImArrayMapSlotConfig
{
    public int SlotCount => 32;
    public int SlotMask  => 31;
    public int KeyMask  => ~31;  
}

[dadhi]

I've ended up passing it as parameter.