kurt function with level parameter should have it's own implementation

[amyskov]

System information

• OS Platform and Distribution (e.g., Linux Ubuntu 16.04): Ubuntu 18.04
• Modin version (modin.__version__): 0.7.3+200.g8e7a568
• Python version: 3.8.3
• Code we can use to reproduce:

Describe the problem

Pandas DataFrame.apply("<func_name>") function calls <func_name> of the DataFrame, so Modin DataFrame should have own implementation of kurt function

Source code / logs