feat: Add Round Robin CPU scheduling algorithm

[harshitrajput2802]

Description of Change

Added an implementation of the Round Robin (RR) CPU scheduling algorithm, a preemptive scheduling technique that allocates CPU time to processes using a fixed time quantum.

This implementation:

• Schedules processes in a FIFO ready queue while respecting process arrival times.
• Ensures that newly arrived processes are admitted to the ready queue before a preempted process is re-queued, matching the standard Round Robin scheduling behavior.
• Supports configurable time quantum values with input validation.
• Includes an independent unit-tick reference implementation for correctness verification.
• Adds regression tests and randomized self-tests to validate the scheduler against the reference implementation.
• Provides comprehensive Doxygen documentation and follows the project's coding conventions, including namespace organization and self-contained examples.

Checklist

• Added description of change
• Added file name matches File name guidelines
• Added tests and example, test must pass
• Added documentation so that the program is self-explanatory and educational
• Relevant documentation/comments is changed or added
• PR title follows semantic commit guidelines
• Search previous suggestions before making a new one, as yours may be a duplicate.
• I acknowledge that all my contributions will be made under the project's license.

Notes: Implemented the Round Robin CPU scheduling algorithm with an independent reference implementation, regression tests, randomized validation, and comprehensive Doxygen documentation.