Add Round Robin CPU scheduling algorithm

[mannanloomba]

Description

This PR adds an implementation of the Round Robin CPU Scheduling Algorithm.

Features

• Implements the preemptive Round Robin scheduling algorithm.
• Supports a configurable time quantum.
• Handles process arrival times.
• Computes Completion Time (CT)
• Computes Turnaround Time (TAT)
• Computes Waiting Time (WT)
• Includes unit tests using assert

Testing

• Verified scheduling results for multiple processes.
• Tested completion time, turnaround time, and waiting time calculations.

[mannanloomba]

Hi maintainers! 👋
Just following up on this PR. Whenever you have time, I'd really appreciate a review. Thank you for maintaining this repository and for your time!