docs: add paraview_docs_uploader

I went ahead and renamed and fully refactor the prepare-doc.sh script (now called paraview_docs_uploader) to:

• Not use env variables for controlling execution since it made its debugging very confusing.
• Use standard arguments using getopts.
• Clean up here and there.
• Enabled it by default in every build, only upload in master and tags, only rename latest in tag commits.

@cory.quammen this is the last iteration. The generated versions.json was wrong when version was nightly or latest, I missed this in the last push. I now tested everything in diff condition and it seems to be working well.

On another note I will push to the webserver the updated versions.json file which should fix the site once and for all. There are some issue connecting at the moment