This commit is trying to DRY up the initiation of the gRPC client in
each command:
It renames the function to CLI instead of GRPC as it actually set up a
CLI client, not a generic grpc client
It also moves the configuration of address, timeout (which is now
consistent) and api to use Viper, allowing users to set it via env vars
and configuration file
This commit rewrites the `routes list` command to use ptables to present
a slightly nicer list, including a new field if the route is enabled or
not (which is quite useful).
In addition, it reworks the enable command to support enabling multiple
routes (not only one route as per removed TODO). This allows users to
actually take advantage of exit-nodes and subnet relays.
