Improve cleanup

[badrogger]

This pull request introduces changes to improve the cleanup processes for single-chain nodes and adds a new utility function for directory content removal. The most significant updates include enhancements to the cleanup_datadir_for_single_chain_node function, the addition of cleanup_dir_content, and updates to the cleanup function in node_cli/operations/fair.py.

Cleanup process improvements:

• Enhanced cleanup_datadir_for_single_chain_node: Modified the logic to iterate over folder names and exclude the shared-space folder when removing regular folders. This ensures more precise cleanup behavior. (node_cli/core/schains.py, node_cli/core/schains.pyL266-R268)

• Updated cleanup function: Added a call to cleanup_dir_content to remove contents of the NFTABLES_CHAIN_FOLDER_PATH directory during cleanup, improving resource management. (node_cli/operations/fair.py, node_cli/operations/fair.pyR248)

Utility function addition:

• New cleanup_dir_content function: Introduced a helper function to remove all contents within a specified directory, including files, links, and subdirectories. This provides a reusable and efficient way to clean directories. (node_cli/utils/helper.py, node_cli/utils/helper.pyR327-R337)

Code organization improvements:

• Imported cleanup_dir_content: Updated imports in node_cli/operations/fair.py to include the newly added cleanup_dir_content function, ensuring its availability for cleanup operations. (node_cli/operations/fair.py, node_cli/operations/fair.pyL58-R59)
• Reordered imports: Adjusted import order in node_cli/operations/fair.py for better readability and adherence to coding standards. (node_cli/operations/fair.py, node_cli/operations/fair.pyL39-R41)