[CARBONDATA-4274] Fix create partition table error with spark 3.1

[CARBONDATA-4274] Fix create partition table error with spark 3.1

Why is this PR needed?
With spark 3.1, we can create a partition table by giving partition
columns from schema.
Like below example:
create table partitionTable(c1 int, c2 int, v1 string, v2 string)
stored as carbondata partitioned by (v2,c2)

When the table is created by SparkSession with CarbonExtension,
catalog table is created with the specified partitions.
But in cluster/ with carbon session, when we create partition
table with above syntax it is creating normal table with no partitions.

What changes were proposed in this PR?
partitionByStructFields is empty when we directly give partition
column names. So it was not creating a partition table. Made
changes to identify the partition column names and get the struct
field and datatype info from table columns.

This closes #4208