engine: Add support for convert_timezone function

[rampage644]

[DanCodedThis]

Started work, maybe will be a problem with merging

[DanCodedThis]

Useful links:
https://en.wikipedia.org/wiki/List_of_tz_database_time_zones

Looking into chrono_tz, since it can parse str to TZ: https://docs.rs/chrono-tz/latest/chrono_tz/

[DanCodedThis]

https://docs.snowflake.com/en/sql-reference/functions/convert_timezone

[DanCodedThis]

working with this, "arrow::array::timezone::{Tz, TzOffset}": https://arrow.apache.org/rust/src/arrow_array/timezone.rs.html

[DanCodedThis]

bug with "select convert_timezone('+00', '2025-01-06 08:00:00+01:00') from some table", i have a check in code that checks if the timezones are the same, and here, even though they are not, it says they are, for now i will remove the check entirely

[DanCodedThis]

bug with "select convert_timezone('+00', '2025-01-06 08:00:00+01:00') from some table", i have a check in code that checks if the timezones are the same, and here, even though they are not, it says they are, for now i will remove the check entirely

fixed for now

[DanCodedThis]

Bugs/Unsupported features/problems we have right now:

1. Inability to return a timestamp since we cannot know in advance the timezone string. -> No soultion.
2. Although the signature doesn't have the ability for the 3 argument version to pass Timestamp with Some(Timezone), it does so. -> Only accept Utf8.
3. Timestamps Timezones always have a value of "+00", so the Timestamp Timezone is only useful for Some(_) or None. -> Only accept Utf8.
4. Utf8 versions of the functions don't yet support the snowflake Local timezone. -> Solvable by just adding that logic