[FEAT] File Nesting support

[chungxon]

Describe the solution you'd like
File nesting allows for related files in a directory to be visually grouped together under a single parent file. It provides a cleaner file tree

Additional context
You can refer to VS Code built-in feature

Before	After

[simonpham]

This is an interesting feature. I'll think of a way to make it extensible for plugins to also declare/contribute to the File Nesting pattern settings.