respect hidden file attribute

currently RipGrep considers a hidden file something starting with ., which is a
long time Linux convention

ripgrep/ignore/src/pathutil.rs

Lines 16 to 24 in c3db8db

	/// Returns true if and only if this file path is considered to be hidden.
	#[cfg(not(unix))]
	pub fn is_hidden<P: AsRef<Path>>(path: P) -> bool {
	if let Some(name) = file_name(path.as_ref()) {
	name.to_str().map(|s| s.starts_with(".")).unwrap_or(false)
	} else {
	false
	}
	}

However the Windows convention of the hidden file attribute is not recognized by
RipGrep. So if you have some files on Windows with the hidden file attribute,
RipGrep will always show them regardless, unless they also happen to start with .

[BurntSushi]

Seems reasonable to me. It looks like we need to check whether the file attributes contain FILE_ATTRIBUTE_HIDDEN.

The one concern I have here is that if this is done naively, it will introduce an additional stat call for every file ripgrep looks at, by default. We should try to avoid that by looking for an existing stat call and reusing its information.

@BurntSushi thanks for fast response

it probably goes without saying, but i am of that opinion that even if this is
implemented it should not be the default, as it seems we are talking about
a performance hit

users should need to opt into this, with the default remaining the faster
option. thank you!