`CircularBufferQueue` method renames

[Argmaster]

• Rename enqueue to pushFront
• Rename enqueue_back to pushBack
• Rename dequeue to popBack
• Rename dequeue_front to popFront
• Rename peek to peekBack

[IntegratedQuantum]

According to wikipedia seems to prefer push/pop instead of enqueue/dequeue and it's also shorter and easier to write, so I suggest we also use that.
So it should be pushBack/pushFront, popBack/popFront and peekBack/peekFront