If the input object is a classic pywwt message, rewrite any relative URLs
that it contains.
The motivation for this function is to allow data exchange from a
Jupyter(Lab) server to the WWT research app. It is possible to publish data
by hooking into the Jupyter server, but that layer of code doesn't always
know the URL at which it is exposed to the world. So, such layers need to
supply relative URLs in their messages, and then the JavaScript layer needs
to modify those messages to turn them into absolute URLs. That's what this
function enables. The input is modified in-place.
If the input object is a classic pywwt message, rewrite any relative URLs that it contains.
The motivation for this function is to allow data exchange from a Jupyter(Lab) server to the WWT research app. It is possible to publish data by hooking into the Jupyter server, but that layer of code doesn't always know the URL at which it is exposed to the world. So, such layers need to supply relative URLs in their messages, and then the JavaScript layer needs to modify those messages to turn them into absolute URLs. That's what this function enables. The input is modified in-place.