[1.0] Take `S: AsRef<Path>` rather than `&Path`

[tgross35]

For API such as https://docs.rs/glob/latest/glob/struct.Pattern.html#method.matches_path, take a more general AsRef<Path> rather than Path.

We may even want to take AsRef<OsStr>, which would allow combining the &str and &Path API

[gavincrawford]

Is this issue related/duplicate? #146