This commit adds a feature for creating a user without password. The
purpose of the feature is reducing attack surface by configuring bad
passwords (CN based auth will be allowed for the user).
The feature can be used with `--no-password` of `etcdctl user add`
command.
Fix https://github.com/coreos/etcd/issues/9590
Currently the auth mechanism doesn't support permissions of range
request. It just checks exact matching of key names even for range
queries. This commit adds a mechanism for setting permission to range
queries. Range queries are allowed if a range of the query is [begin1,
end1) and the user has a permission of reading [begin2, range2) and
[begin1, end2) is a subset of [begin2, range2). Range delete requests
will follow the same rule.
This commit adds a new subcommand "user add" to etcdctlv3. With the
command users can create a user for the authentication.
Example of usage:
$ etcdctlv3 user add user1
Password of user1:
Type password of user1 again for confirmation:
