feat: Add support for both basic and Cognito bearer auth for Airflow API

[pymonger]

Summary

This PR adds support for both legacy Basic Auth and Cognito Bearer Token authentication (OAuth2 and InitiateAuth flows) for submitting DAG runs to the Airflow API. It also updates the router config schema, documentation, and adds comprehensive unit tests.

Key Changes

• submit_dag_by_id.py now supports:
  • auth_method: basic (legacy username/password)
  • auth_method: bearer with cognito_token_method: oauth2 (OIDC/JWT)
  • auth_method: bearer with cognito_token_method: initiate_auth (AWS-native)
• Router config schema updated to allow all relevant fields for both auth methods
• README updated with full example configs and usage guidance
• New unit tests for all authentication modes and token refresh logic
• Pre-commit, linting, and formatting compliance
• Version bumped to 0.0.2

Motivation

• Enables secure, flexible authentication for Airflow APIs behind ALB/API Gateway with Cognito
• Provides clear documentation and examples for users
• Ensures robust, tested, and maintainable code

Checklist

• Code and tests updated
• Documentation updated
• Pre-commit hooks passing
• Version bumped

[LucaCinquini]

@pymonger : impressive amount of work, thank you. I have a few questions to discuss later today.