🔇 ACA-Py should not log credential attributes

[ff137]

Credential attributes can contain private information, and it should be obfuscated in logs. Examples of where it is currently logged:

acapy_agent.messaging.base_handler INFO Received v2.0 credential offer message: {...}

The above log prints raw values for credential attributes, as well as a base64 encoding that contains it as well. Both should be obfuscated.