"""Convert JSON list to list of selected values.

This function processes a value that can be in various formats and converts it into a list. 
The function handles the following cases:
- If the value is `None` or an empty string, it returns an empty list.
- If the value is already a list, it returns the list as is.
- If the value is a string, it treats it as a comma-separated list of values, strips whitespace, 
  converts each value to lowercase, and returns a list of these processed values.
- For any other type of value, it returns the value unchanged.

Args:
    value (Any): The input value to be processed. Can be `None`, a string, a list, or any other type.

Returns:
    List[Any]: A list of processed values. If the input is `None` or an empty string, returns an empty list. 
    If the input is a list, returns the list unchanged. If the input is a string, returns a list of 
    processed values. For any other type, returns the value unchanged.
"""
You should write code starting with:
from typing import Any, List

def prepare_value(value: Any) -> List[Any]:
    # TODO: Implement this function based on the docstring.
    pass

