[Feature Request] Security plugin integration for grpc-transport plugin

[finnegancarroll]

Is your feature request related to a problem? Please describe

Implement security features and integrate with OpenSearch security plugin for production readiness of experimental gRPC transport. It should be the case that security settings for existing http transport maps cleanly onto newly introduced grpc-transport, providing configurable TLS, AuthN, and AuthZ for this new transport implementation.

Describe the solution you'd like

Security Requirements

TLS/Certificate Management

• Add and extend NetworkPlugin.SecureAuxTransport interface
• Configure certificate loading from security plugin
• Allow enable TLS on grpc-transport
• Maintain separation of security settings between client/server transports

Authentication/Authorization

*Additional research needed here to determine the extent these are handled by the security plugin.

• Provide framework for user authentication
• Provide framework for enforcing role-based access control

Related component

Plugins

Describe alternatives you've considered

Leaving the grpc-transport as plaintext. TLS may not be useful for if users do not plan on making this endpoint public. Similarly AuthN/AuthZ is situational.

Additional context

No response