feat: Support cast to BIGINT before aggregation

[nehanene15]

Closes Issue #416

• Adds support for specifying a default_cast for any column
• Adds flag --cast-to-bigint which automatically casts any int32 column into int64 before aggregations. This is useful when running into INT overflow errors.

[nehanene15]

/gcbrun

[crfacundo]

Hi, when i use --cast-to-bigint i have an error because int64 is not a datatype in teradata. Is there any possibility to cast to bigint datatype?

[nehanene15]

Hi, when i use --cast-to-bigint i have an error because int64 is not a datatype in teradata. Is there any possibility to cast to bigint datatype?

You can see this example on how to cast to a different data type such as decimal/numeric.