text: Title: Automatic argument conversion and validation for `Literal`
  Body: Look at this moment:
  ```py
  def foo(a: Literal[1, 2, 3]): ...
  ```
  ```robot
  Something
      foo    1
  ```
  
  Currently, robot will send a `"1"` to this function, which is invalid, I would expect robot to convert the string to an int.
  
  - #4630