Add Support for Negotiate authentication to CachedSchemaRegistryClient

[danielwagn3r]

Description

We've a schema registry which is running in a kerberized environment and with the current schema registry client only basic authentication is supported.

Adding a feature like with Kafka it self (protocol SASL_SSL and mechanism GSSAPI) could solve the problem.

Another work would be #530 which already has been closed.

How to reproduce

Try to get CachedSchemaRegistryClient running with a kerberized https://github.com/hortonworks/registry.

Checklist

Please provide the following information:

• [ ] A complete (i.e. we can run it), minimal program demonstrating the problem. No need to supply a project file.
• [x] Confluent.Kafka nuget version: 1.1.0
• [x] Apache Kafka version. 2.0.0
• [ ] Client configuration.
• [x] Operating system. Windwos 10
• [ ] Provide logs (with "debug" : "..." as necessary in configuration).
• [ ] Provide broker log excerpts.
• [ ] Critical issue.

[mhowlett]

current near term plans include adding support for SSL auth only.

[danielwagn3r]

Any ideas on Kerberos Negotiate, HortonWorks Schema Registry seems to be running often in a kerberized environment.

What about a possibility running the deserializer without a schema registry?