feat(structure): implements circular queue

[zFl4wless]

This PR implements a circular queue, which has already been started but never finished in #70
Because we now have a general interface for the Queue, I decided to create a new branch with the implementation and create the Circular Queue with the already existing interface instead of fighting with potential merge conflicts.

[appgurueu]

I'm not sure whether CircularQueue should implement the Queue interface. Yes, it provides the same methods with the same signatures. But the semantics are different. Interfaces are for different classes implementing the same semantics.