This commit adds two flags to etcdctl:
1. `--password` flag to etcdctl as a global option. It can be used for
specifying password for authentication required for the command
execution.
2. `--new-user-password` flag to `etcdctl user add`. It can be used
for specifying password of newly created user by the command.
The main motivation of the flags is allowing user to have : in its
name.
Fix https://github.com/coreos/etcd/issues/9691
Migrate command accepts a datadir and an optional user-provided
transformer function that transform v2 keys to v2 keys.
Migrate command then builds a v3 backend state based on the existing
v2 keys and the output of the transformer function.
This commit adds a functionality of attaching an auth token to gRPC
connection as a per RPC credential.
For doing this, this commit lets clientv3.Client.Dial() create a
dedicated gRPC connection for doing authentication. With the dedicated
connection, the client calls Authenticate() RPC and obtain its
token. The token is attached to the main gRPC connection with
grpc.WithPerRPCCredentials().
This commit also adds a new option --username to etcdctl (v3). With
this option, etcdctl attaches its auth token to the main gRPC
connection (currently it is not used at all).
Gyuho Lee