Enable transmitting the discovered "raw" features over the gRPC API.
Extend pkg/api/feature with protobuf and gRPC code. In this, utilize
go-to-protobuf from k8s code-generator for auto-generating the gRPC
interface from golang code. The tool can be Installed with:
go install k8s.io/code-generator/cmd/go-to-protobuf@v0.20.7
The auto-generated code is (re-)generated/updated with "make apigen".
