Improve code readability by adding type hints

[shima004]

This pull request updates the initialization of several class attributes across multiple files to include explicit type annotations. This change improves code clarity, helps with static type checking, and enhances maintainability by making the expected types of instance variables clear.

Type annotation improvements:

• Added explicit type annotations to instance variables in the ExtendAction class constructor in extend_action.py.
• Added explicit type annotations to instance variables in the CommandExecutor class constructor in command_executor.py.
• Added explicit type annotations to instance variables in the CommandPicker class constructor in command_picker.py.