RequestConnector: read basic auth credentials from env

[maghibus]

RequestConnector can now read Basic Authentication credentials from environment variables, making configuration simpler and more suitable for containerized/CI environments.

What changed

• Added support for reading REQUEST_BASIC_USERNAME and REQUEST_BASIC_PASSWORD from env.
• RequestConnector uses these credentials when present.

Why

• Avoid storing credentials in config files.
• Improve portability across environments (dev/test/prod).

How to test

1. Set REQUEST_BASIC_USERNAME and REQUEST_BASIC_PASSWORD.
2. Start the gateway with a configured Request Connector.
3. Verify the request is authenticated correctly (or logs confirm env credentials are used).

Notes
If env vars are not set, previous behavior remains (to confirm).

[CLAassistant]

All committers have signed the CLA.