Make primaryKey and other column configs case insensitive

The primaryKey and other configs should be case insensitive.

Test case to reproduce - 
test("Test primary key case sensitive") {
withTempDir { tmp =>val tableName = generateTableName // Create a partitioned table spark.sql( s""" |create table $tableName ( | id int, | name string, | price double, | ts long, | dt string |) using hudi | tblproperties (primaryKey = 'ID' | ) | partitioned by (dt) | location '${tmp.getCanonicalPath}'""".stripMargin)
spark.sql( s""" | insert into $tableName | select 1 as id, 'a1' as name, 10 as price, 1000 as ts, '2021-01-05' as dt""".stripMargin)
checkAnswer(s"select id, name, price, ts, dt from $tableName")( Seq(1, "a1", 10.0, 1000 , "2021-01-05")
)
}
}

## JIRA info

- Link: https://issues.apache.org/jira/browse/HUDI-8172
- Type: Improvement
- Fix version(s):
- 1.1.0