Add Depth Limitation Flag to Directory Tree Generator

[sm18lr88]

This pull request adds a new feature to the RP Tree directory tree generator. Users can now limit the depth of the generated directory tree using the -l or --level flag.

This enhancement allows for more control over the output, especially useful for large directory structures.

The implementation includes modifications to the rptree.py, cli.py, and main.py files to support this new functionality.