Casting DateTime types to Numeric types should be supported

Currently we can cast numeric types such as Int / BigInt to Date / Time / Timestamp.

Example

Int 1 to Date: 1970-01-01
Int 1 to Time: 00:00:00.001
Int 1 to Timestamp: 1970-01-01 00:00:00.001

Casting Date / Time / Timestamp to Int / BigInt should also be supported, as they are internally stored as BigInt. Currently we get a NumberFormatException for explicit casts on these types.