Some `datafusion-spark` expressions are missing the physical implementation

[andygrove]

Describe the bug

I wanted to add base64 support in Comet using the expression from datafusion-spark, but it has no implementation, so I had to implement a custom version in Comet. This doesn't seem ideal.

  fn invoke_with_args(&self, _args: ScalarFunctionArgs) -> Result<ColumnarValue> {                                                                                                                     
      exec_err!("invoke should not be called on a simplified {} function", self.name())                                                                                                                
  }                                                                                                                                                                                                    

To Reproduce

No response

Expected behavior

No response

Additional context

https://discord.com/channels/885562378132000778/1413656077014143008/1499408538429030421

[coderfender]

Let me take on this and also other expressions to completely remove simplify methods in df-spark crate given comet (and hopefully other downstream consumers) use it