[Variant] Align cast logic for `variant_get` to cast kernel

**Is your feature request related to a problem or challenge? Please describe what you are trying to do.**

Currently, we only support safe cast, but no lossy cast(e.g., 123.34(Decimal) -> 123(Int)), we need to support this after #8086 and #8873

**Describe the solution you'd like**

Add a lossy cast for all data types in `variant_get`, we may need to do each data type separately.

**Describe alternatives you've considered**

**Additional context**