Validate links during Jenkins build

[caufieldjh]

One of the primary functions of this project is to provide stable URLs to transformed ontologies.
Consequently, we should keep track of all new URLs we create, and do the following:

• Append new URLs to a specific tracking file, independent of the tracking.yaml used to list OBO versions
• Check URL validity and resolvability during Jenkins build
• Create redirects?

[caufieldjh]

This functionality can apply to KG-Hub in general, and supported through a manifest file as described here: Knowledge-Graph-Hub/knowledge-graph-hub.github.io#1

All URLs should be unique (i.e., don't replace existing graph files with new versions in-place, create new paths for new versions) so if a link is moved the original URL will still be in the manifest. It can be obsoleted and redirected, though I'm not sure how to handle this automatically without checking if all URLs resolve at each update of the manifest.