Feature: support Timestamp with TZ for function to_unixtime

[xudong963]

Is your feature request related to a problem or challenge?

> select to_unixtime(arrow_cast('2020-01-01 00:10:20.123'::timestamp, 'Timestamp(Second, Some("America/New_York"))'));
Execution error: Unsupported data type Timestamp(Second, Some("America/New_York")) for function to_unixtime

Describe the solution you'd like

No response

Describe alternatives you've considered

No response

Additional context

Timestamp without TZ is supported for to_unixtime

> select to_unixtime(arrow_cast('2020-01-01 00:10:20.123'::timestamp, 'Timestamp(Second, None)'));
+------------------------------------------------------------------------------------------+
| to_unixtime(arrow_cast(Utf8("2020-01-01 00:10:20.123"),Utf8("Timestamp(Second, None)"))) |
+------------------------------------------------------------------------------------------+
| 1577837420                                                                               |
+------------------------------------------------------------------------------------------+

[Omega359]

This works on main:

query I
select to_unixtime(arrow_cast('2020-01-01 00:10:20.123'::timestamp, 'Timestamp(Second, Some("America/New_York"))'));
----
1577855420

[Omega359]

I think I fixed this earlier this month in #14490