[SPARK-21878] [SQL] [TEST] Create SQLMetricsTestUtils

[gatorsmile]

What changes were proposed in this pull request?

Creates SQLMetricsTestUtils for the utility functions of both Hive-specific and the other SQLMetrics test cases.

Also, move two SQLMetrics test cases from sql/hive to sql/core.

How was this patch tested?

N/A

[gatorsmile]

cc @cloud-fan

[gatorsmile]

The above two test cases are moved to sql/execution/metric/SQLMetricsSuite.scala

[SparkQA]

Test build #81275 has finished for PR 19092 at commit 3dad127.

• This patch fails due to an unknown error code, -9.
• This patch merges cleanly.
• This patch adds the following public classes (experimental):
• class SQLMetricsSuite extends SparkFunSuite with SQLMetricsTestUtils with SharedSQLContext
• trait SQLMetricsTestUtils extends SQLTestUtils
• class SQLMetricsSuite extends SQLMetricsTestUtils with TestHiveSingleton

[gatorsmile]

retest this please

[SparkQA]

Test build #81276 has finished for PR 19092 at commit 3dad127.

• This patch passes all tests.
• This patch merges cleanly.
• This patch adds the following public classes (experimental):
• class SQLMetricsSuite extends SparkFunSuite with SQLMetricsTestUtils with SharedSQLContext
• trait SQLMetricsTestUtils extends SQLTestUtils
• class SQLMetricsSuite extends SQLMetricsTestUtils with TestHiveSingleton

[cloud-fan]

LGTM

[gatorsmile]

Thanks! Merging to master.