Major Description
As the result of to_timestamp become consistent with the SQL configuration spark.sql.timestmapType and there is already a SQL function to_timestmap_ntz, we need new function to_timestamp_ltz to construct timestamp with local time zone literal.
syntax:
```
to_timestamp_ltz(timestamp_str_column[, fmt])
to_timestamp_ltz(timestamp_column)
to_timestamp_ltz(date_column)
```
