Add support for new test topic and improve error logging in writers

[oto-macenauer-absa]

This pull request introduces support for a new public.cps.za.test topic across the configuration, schema, and writers, and adds a comprehensive configuration validation test suite. The changes ensure that the new topic is handled end-to-end, while also improving error logging in writer modules and enforcing config/schema correctness with new tests.

Support for new topic public.cps.za.test:

• Added public.cps.za.test topic with associated user access in conf/access.json.
• Introduced a new schema for the test topic in conf/topic_test.json.
• Updated src/event_gate_lambda.py to load the new topic schema and switched config loading to config.dev.json.

Writer enhancements for the new topic:

• Added postgres_test_write function in src/writer_postgres.py to handle inserts for the new topic, and updated the main write logic to support it [1] [2].

Improved error logging:

• Enhanced error messages in src/writer_eventbridge.py, src/writer_kafka.py, and src/writer_postgres.py to provide more context on unknown exceptions [1] [2] [3].

Configuration and schema validation tests:

• Added tests/test_conf_validation.py to verify that config files contain required keys, access files have correct structure, and topic schemas are well-formed.

Release notes
Release notes:

• Added unit test validation topic schemas
• Added schema for test topic (will be used to e2e test)
• Improved logging - added info witch writer failed

Related work
Closed #48