home: Consider replacing the deprecated SHGetFolderPathW with SHGetKnownFolderPath

[ChrisDenton]

Currently home uses SHGetFolderPathW to get the home directory on Windows:

cargo/crates/home/src/windows.rs

Lines 19 to 26 in bdef274

	let mut path: Vec<u16> = Vec::with_capacity(MAX_PATH as usize);
	match SHGetFolderPathW(0, CSIDL_PROFILE as i32, 0, 0, path.as_mut_ptr()) {
	S_OK => {
	let len = wcslen(path.as_ptr());
	path.set_len(len);
	let s = OsString::from_wide(&path);
	Some(PathBuf::from(s))
	}

SHGetFolderPathW is marked as deprecated and is simply a wrapper around SHGetKnownFolderPath. It might be better to use the not-deprecated function.

This would allow home to support user directories longer than MAX_PATH if, in the future, the OS does. I do however think that's very unlikely so this change isn't that important.