Describe the enhancement requested

Summary

The format of a Timestamp may include an IANA/Olson timezone identifier, but this is not currently supported by the C# implementation in TimestampArray.

From the schema:

The time zone is a string indicating the name of a time zone, one of:

 * As used in the Olson time zone database (the "tz database" or
   "tzdata"), such as "America/New_York"
 * An absolute time zone offset of the form +XX:XX or -XX:XX, such as +07:30

Acceptance Criteria

• TimestampArray must support IANA/Olson timezone identifiers.

Reporter: Adam Szmigin / @mr-smidge

_{Note: This issue was originally created as ARROW-9515. Please see the migration documentation for further details.}

Copied from apache/arrow#25583