Drop the gRPC communication to nfd-master and connect to the Kubernetes
API server directly when updating NodeResourceTopology objects.
Topology-updater already has connection to the API server for listing
Pods so this is not that dramatic change. It also simplifies the code
a lot as there is no need for the NFD gRPC client and no need for
managing TLS certs/keys.
This change aligns nfd-topology-updater with the future direction of
nfd-worker where the gRPC API is being dropped and replaced by a
CRD-based API.
This patch also update deployment files and documentation to reflect
this change.
Add tests covering the basic functionality of NodeFeatureRule objects,
covering different feature types ("flag features", "attribute features"
and "instance features") as well as backreferencing (using the output of
previously run rules) and templating. The test relies on the "fake"
feature source and its default configuration.
