Implement "Generate Docstring" & "Generate Test Cases" in CLI and Neovim

[xArbisRox]

Checklist

• This is a new feature, not a refactoring suggestion
• I have checked for this feature in the Sourcery documentation
• I have checked there are no open requests referencing the same feature

Description

After moving from PyCharm to Neovim, I realized that your valuable "Generate Docstring" and "Generate Test Case" functionalities are not available in Neovim nor the CLI.

It would be valuable to have these functionalities available in tools besides VSCode and PyCharm, potentially with prioritization on the CLI, as this would allow usage without dependency on the IDE/editor.