maintain #anchors in file:// uris

[pixelb]

This is coming from ptyxis issue 516

I.e., almost all terminals will correctly propagate the #anchor in file:///foo/bar.html#anchor. Unfortunately ptyxis drops it due to libportal use.

The use case I have is I'm going to markup --help from all of coreutils to link to the appropriate part of a local manual (a remote manual is fine, but a local manual should work (as it does with most other terminals))