Breadcrumbs should be generated in the html to prevent layout shift

Currently they are generated by the javascript after the page loads, which means there's a layout shift.

If you keep reloading any page there's an obvious content shift, e.g. here: https://dotnet.github.io/docfx/api/Docfx.Dotnet.DotnetApiCatalog.html

At the very least, the breadcrumbs element should at least have a ` ` in it to preserve space.

Ideally things like TOC would also be generated, but at least they don't shift content.