[3.12] GH-119054: Add "Querying file type and status" section to pathlib docs (GH-119055) (#119952)

Add a dedicated subsection for `Path.stat()`-related methods, specifically
`stat()`, `lstat()`, `exists()`, `is_*()`, and `samefile()`.

(cherry picked from commit 81d63362302187e5cb838c9a7cd857181142e530)