Added functional operations to circular_linked_list.c

[swayam9705]

Description of Change

Converted the circular linked list implementation from an interactive script to a functional library.

Changes: Encapsulated core operations into standalone functions.

Benefit:

1. Operations are no longer dependent on stdin/user prompts
2. Making the data structure reusable for external modules and automated unit testing.

References

This PR is with reference to PR #1531

Checklist

• Added description of change
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• Added tests and example, test must pass
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