[SPARK-17680][SQL][TEST] Added a Testcase for Verifying Unicode Character...

[SPARK-17680][SQL][TEST] Added a Testcase for Verifying Unicode Character Support for Column Names and Comments

### What changes were proposed in this pull request?

Spark SQL supports Unicode characters for column names when specified within backticks(`). When the Hive support is enabled, the version of the Hive metastore must be higher than 0.12,  See the JIRA: https://issues.apache.org/jira/browse/HIVE-6013 Hive metastore supports Unicode characters for column names since 0.13.

In Spark SQL, table comments, and view comments always allow Unicode characters without backticks.

BTW, a separate PR has been submitted for database and table name validation because we do not support Unicode characters in these two cases.
### How was this patch tested?

N/A

Author: gatorsmile <gatorsmile@gmail.com>

Closes #15255 from gatorsmile/unicodeSupport.