initial directory listing support

[b5]

• now with actual HTML
• breadcrumb headers
• icons for 64 file extensions (matching kubo)
• human readable file sizes (via a new iroh-util func, cc @faassen for CLI usage)
• sizes are in SI units (MiB, KiB, GiB), too nerdy?
• all data prep handled on the rust side, with no helper functions in template code
• use include_str! for easier asset maintenance

re-interprets the kubo template with iroh colors (I don't think we should be screwing with end-user expectations too much for this first release), but help links point to iroh to avoid bombing kubo maintainers with iroh issues:

punted until later:

• root directory size
• load time indicator
• proper tests to ensure directory template doesn't break everything

closes n0-computer/beetle#258

[dignifiedquire]

this will not do what you want, if base is empty this will produce //<path_el>.

match prev.get("path") {
  Some(base) => format!("/{}/{}", base, encode(path_el)),
  None => format!("/{}", encode(path_el)),
}

should be closer to what you want

[dignifiedquire]

actually looking at the whole structure this can be simplified to

match accum.last().and_then(|prev| prev.get("path")) {
    Some(base) => format!("/{}/{}", base, encode(path_el)),
    None => format!("/{}", encode(path_el)),
}

[dignifiedquire]

can I get a todo at least for writing a test for this?