This commit deprecates/replaces the old field `sat_per_byte` with
`sat_per_vbyte`. While the old field suggests sat per byte, it’s
actually using sat per virtual byte. We use the Hidden param to hide all
the deprecated flags. These flags won't show up in help menu onwards,
while stay valid that can be passed from cli. Thus bash scripts
referencing these fields won't be broken.
In order to be able to register the subservers with the root grpc server
before we have all dependencies available, we wrap them in an
GrpcHandler struct. This struct will initially hold an empty reference
to the subservers, which allows us to register with the GRPC server, and
later populate and create the subserver instance.
The logger string used to identify the wtclient and wtclientrpc loggers
was the same, leading to being unable to modify the log level of the
wtclient logger as it would be overwritten with the wtclientrpc's one.
To simplify things, we decide to use the existing RPC logger for
wtclientrpc.
