Take `impl Into<Bstr>` in `gix_url::parse`

[wiiznokes]

Summary 💡

Take impl Into<Bstr> in gix_url::parse

Motivation 🔦

To be able to give &str. Also, bstr is not reexported.

[Skgland]

Wouldn't impl AsRef<BStr> be more typical rather than impl Into<&'_ BStr>?