Enhance CREATE INDEX syntax for functional index

Currently, user can create index using sql as follows: 

`create index idx_datestr on $tableName using column_stats(ts) options(expr='from_unixtime', format='yyyy-MM-dd')`

Ideally, we would to simplify this further as follows:

`create index idx_datestr on $tableName using column_stats(from_unixtime(ts, format='yyyy-MM-dd'))`

## JIRA info

- Link: https://issues.apache.org/jira/browse/HUDI-7029
- Type: Task
- Epic: https://issues.apache.org/jira/browse/HUDI-512
- Fix version(s):
- 1.1.0

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## Comments

24/Jul/24 07:13;codope;Need to enahnce sql grammar;;;