Missing PATH and PATH_FS for FS operations

[WebReflection]

I have noticed that, differently from Pyodide and MicroPython for WASM, where some of these utilities are hidden behind a _module field, I can't seem to find these commonly available exports from Emscripten in here, so that I need to manually provide a PATH_FS.resolve(path) functionality and a PATH.dirname(path) too.

On top of that, it'd be lovely to have a FS.mkdirTree(pathDir) utility too, but that's something I can eventually workaround as long as previous utilities are available.

If there is no interest in exposing more paths related utilities, please let me know so I can think about a better solution (but we know user-land code for foreign FS can easily fail in various circumstances).

Thank you!