[SPARK-11970][SQL] Adding JoinType into JoinWith and support Sample in Dataset API

Except inner join, maybe the other join types are also useful when users are using the joinWith function. Thus, added the joinType into the existing joinWith call in Dataset APIs.

Also providing another joinWith interface for the cartesian-join-like functionality.

Please provide your opinions. marmbrus rxin cloud-fan Thank you!

Author: gatorsmile <gatorsmile@gmail.com>

Closes #9921 from gatorsmile/joinWith.