refactor(SQO): Modularise codebase, create a single source of truth for config, add test framework, review all components.

[MoonBoi9001]

Description:

This pull request reworks the Service Quality Oracle, refactoring it into a fully modular, and more easily testable system. Key improvements include a new modular architecture, centralised configuration management, standardised retry logic, and updated CI/CD workflows.

Key Changes:

1. Modular Architecture:
The application's core logic, previously handled by a few tightly-coupled scripts (including issuance_eligibility_oracle_core.py and issuance_data_access_helper.py), has been refactored into distinct modules under src/models. Each module has a specific responsibility, making the system easier to maintain and test:

• bigquery_data_access_provider.py: Manages all BigQuery interactions.
• blockchain_client.py: Handles blockchain operations with RPC failover.
• eligibility_pipeline.py: Contains the core eligibility logic.
• subgraph_data_access_provider.py: Interfaces with the subgraph.
• scheduler.py: Manages the scheduling of the oracle's run.
• service_quality_oracle.py: Orchestrates the overall workflow, integrating the other modules.

2. Centralised Configuration (src/utils/configuration.py):

• Replaced config_loader.py with the more robust configuration.py module.
• Introduced ConfigLoader for loading settings from config.toml and substituting environment variables.
• Added a CredentialManager class to handle Google Cloud credentials.
• Implemented validation for configuration fields, raising ConfigurationError for missing or invalid values.

3. Standardised Retries (src/utils/retry_decorator.py):

• Created a new, reusable retry_with_backoff decorator using the tenacity library to provide a consistent exponential backoff strategy.
• The SlackNotifier has been updated to use this new decorator, simplifying its implementation.

4. Build and Dependency Updates:

• Docker: Dockerfile and docker-compose.yml have been updated to support the new application structure.
• Dependencies: pyproject.toml updated.
• Formatting: A new custom formatter was introduced in scripts/custom_formatter.py and integrated into the linting script scripts/ruff_check_format_assets.sh.
• Configuration: config.toml.example has been updated to reflect the new configuration.

5. Utility and Code Quality Improvements:

• key_validator.py: Refactored validate_and_format_private_key to be more concise. It now raises a KeyValidationError on failure instead of returning a result object.
• slack_notifier.py: Simplified by removing manual retry logic in favor of the new decorator.
• Error Handling: Implemented consistent error handling across modules.

6. Structured Testing Framework (tests/):

• Established a formal testing suite by adding new test files for key components:
  • test_blockchain_client.py
  • test_configuration.py
  • test_eligibility_pipeline.py
  • test_scheduler.py
  • test_service_quality_oracle.py

7. CI/CD and Documentation:

• The GitHub Actions workflows (ci.yml, tests.yml) have been updated to align with the new project structure and testing framework.
• The README.md has been updated to reflect the new architecture and provide clear setup and usage instructions.