[client] KUDU-3472 Java client API to import JWT

This patch adds one new method into AsyncKuduClient and KuduClient API
to set a JWT (JSON Web Token) to be used for authentication.  The newly
introduced API matches the one introduced in the C++ Kudu client.

Change-Id: Ic43bd1219f4613e9cac11762726a5d6d2cdc764b
Reviewed-on: http://gerrit.cloudera.org:8080/19836
Tested-by: Alexey Serbin <alexey@apache.org>
Reviewed-by: Alexey Serbin <alexey@apache.org>
4 files changed