[FEATURE] Skip existing files and directories

[pyousefi]

Feature Description

Growing the tree structure should allow the process to run and add newly added directories and files. This requires skipping already existing files and directories.

Problem Statement

I am frustrated with having to blow away the entire structure of my project for this tool to work when I make additions to my tree.

Proposed Solution

Add a parameter to skip existing folders and files during creation.

Alternative Solutions

A "sync" approach would keep the directory and file structure in sync with the given tree by adding or deleting.

Example Use Case

tree2dir generate -f mytree.txt -s