Any backward slash characters do not get treated correctly and within
the relative link calculations.

The base document path contains a backslash on Windows and Sphinx's
relative_uri function needs to see everything as a unix-style path
in order to compute the correct relative path.
Refs #19678

Stop warnings/errors coming out with no source information.

Docutils interprets these as references by default but we just want plain
.text

Without an escape character docutils processes these as links.

re #14381

re #14381

re #14381

This created an infinite loop which is now gone. The next step
is to correctly get the source directory.