Flag to support legacy converted types

[pacman82]

Inspired by #284 and #285.

The switch to logical types allowed odbc2parquet to select better fitting types in many situations. However, if logical types are not supported by the next step in the data pipeline restricting odbc2parquet to only choose schemas which can be expressed within the legacy converted types may be preferable.

Ping @leo-schick.

See also: https://github.com/apache/parquet-format/blob/master/LogicalTypes.md#deprecated-timestamp-convertedtype

[pacman82]

See also upstream issue about supporting other Time units than Nanoseconds for Time:
apache/arrow-rs#3362