feat: add paused() method to Consumer

[harrold-mussa]

What

This PR implements the paused() method for the High-Level Consumer. This allows users to retrieve a list of the partitions that are currently paused for the consumer instance, mapping directly to the underlying rd_kafka_paused_partitions functionality in librdkafka.

Implementation Strategy:

• Added Consumer_paused to src/confluent_kafka/src/Consumer.c.
• Utilized c_parts_to_py to convert the C rd_kafka_topic_partition_list_t into a Python list of TopicPartition objects.
• Added a type hint in src/confluent_kafka/cimpl.pyi to support IDE autocompletion and static analysis.

Checklist

• Contains customer facing changes? Including API/behavior changes
• Did you add sufficient unit test and/or integration test coverage for this PR?
• Unit tests have been added in tests/test_Consumer.py to verify the method returns the expected list type and correctly reflects the state of the consumer.

References

JIRA:
Issue: Fixes #1793

Test & Review

Manual Verification: I built the C extension locally and verified the paused() method using a targeted unit test.

Command: PYTHONPATH=src pytest tests/test_Consumer.py

Verification: Confirmed c.paused() returns a list of TopicPartition objects.

Notes on Environment: Due to a local librdkafka version mismatch (v2.3.0 vs required v2.13.0), the full suite was skipped, but the specific logic for paused() was isolated and verified as functional..

Open questions / Follow-ups

CI Feedback: Awaiting results from GitHub Actions to confirm cross-platform compilation (specifically for Windows/macOS runners)

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