[FEA] support spark.sql.legacy.timeParserPolicy

[revans2]

Is your feature request related to a problem? Please describe.
When parsing dates and times it would be good if we could also follow the spark.sql.legacy.timeParserPolicy config.

[sameerz]

Trace through where this config is used in Spark and if the plugin cannot match the same functionality, fall back to the CPU.

[andygrove]

The default value for spark.sql.legacy.timeParserPolicy is EXCEPTION in which case Spark throws an exception if any of the following functions are unable to parse data using the specified pattern, and suggests that the conversion may work with LEGACY. If the config is set to CORRECTED then the conversion will return null instead of throwing an exception.

• unix_timestamp
• from_unixtime
• from_utc_timstamp
• to_unix_timestamp
• to_utc_timestamp
• to_date
• to_timestamp
• date_format

I propose that we follow the same behavior but fall back to CPU for LEGACY for these functions until we have a reason to add support for specific legacy formats that are no longer supported in Spark 3.0 and later. If we do end up doing that we can then just fall back to CPU for legacy formats that we do not support.

[andygrove]

Resolved by #1113 for functions, and I filed a follow on #1111 for handling this for CSV reads