Write operation ids as hex instead of bytes

[susodapop]

Thrift responses include operationId and sessionId guids as byte arrays. We print these in our logs and include them in ServerOperationError responses. But they aren't human readable. We can use Python's built-in UUID library to convert them into human-readable hex strings. In the case of query ids, these can be directly tied back to Databricks Query History API responses.

[susodapop]

I implemented this is one spot here: #159 with the get_session_id_hex method. But we're still writing out bytes-like GUIDs in numerous other places in the code base such as here, here, and here.