[SPARK-15019] [SQL] Propagate all Spark Confs to HiveConf created in HiveClientImpl

[yhuai]

What changes were proposed in this pull request?

This PR makes two changes:

1. We will propagate Spark Confs to HiveConf created in HiveClientImpl. So, users can also use spark conf to set warehouse location and metastore url.
2. In sql/hive, HiveClientImpl will be the only place where we create a new HiveConf.

How was this patch tested?

Existing tests.

[SparkQA]

Test build #57374 has finished for PR 12791 at commit 9364a9d.

• This patch passes all tests.
• This patch merges cleanly.
• This patch adds no public classes.

[andrewor14]

LGTM