Feature request: max depth for file nodes

[dangerzone]

Flags -L for max depth and -d for showing only already dirs already exist, but it would be useful to set a max depth limit for where file nodes are shown. This wouldn't limit directory nodes, those can still be set using the -L flag

Instead of the not-shown files, it can show something like [+N additional files] or something similar

Motivation:

For my particular use case of operating on very large and deeply nested directories - (I have to feed the directory structure to an LLM), it's important to limit the directory tree output to the most important information. This flag will have lstr provide a high-level overview of the project structure without too much unnecessary distracting information.