Ability to set an initial size in addition to `capacity`?

[ithinkicancode]

Motivation

Depending on the underlying data structure, initializing it to a known size that fits user's use pattern might be a good optimization.

Considerations

If I'm not mistaken, zio.internal.MutableConcurrentQueue is currently used as the underlying data structure. I'm not familiar with the characteristics or the implementation of this data structure. Perhaps this ticket won't be applicable or useful to MutableConcurrentQueue.