New credential provider for replicating to the cloud

For a more detailed explanation, see: Hive Replication Keystore Management

In ReplDumpTask, if the following new config is provided in HiveConf:

• hive.repl.cloud.credential.provider.path

then the HS2 credstore URI scheme, contained by HiveConf with key hadoop.security.credential.provider.path, should be updated so that it will start with new scheme: hiverepljceks. For instance:

jceks://file/path/to/credstore/creds.localjceks

will become:

hiverepljceks://file/path/to/credstore/creds.localjceks

This new scheme, hiverepljceks, will make Hadoop to use a new credential provider, which will do the following:

1. Load the HS2 keystore file, defined by key hadoop.security.credential.provider.path
2. Gets a password from the HS2 keystore file, with key: hive.repl.cloud.credential.provider.password
3. This password will be used to load another keystore file, located on HDFS and specified by the new config mentioned before: hive.repl.cloud.credential.provider.path. This contains the cloud credentials for the Hive cloud replication.