Archive osgithub by moving required code into Reports and Actions Registry

Description

osgithub was originally intended to provide a generic shared interface for interacting with the GitHub API. But in reality, we've had very different use cases each time we've wanted to get something from GitHub. Consequently, we've only used the osgithub library in two places - Reports and Actions Registry. Maintaining osgithub as a separate library now creates overhead that may not be justified by its limited reuse.

We should investigate and migrate the required osgithub functionality directly into the two applications that currently depend on it, and then archive the osgithub repository.

Related slack discussion.

How will we know when it's done?

• Identify all current consumers of osgithub.
• Move the required code into Reports.
• Move the required code into Actions Registry.
• Remove osgithub as a dependency from both applications.
• Archive osgithub repository on GitHub
• Archive osgithub package on PyPI

Start by identifying the current osgithub consumers in Reports and Actions Registry and documenting which functionality each application requires. Move the required code into both applications, remove the dependency, then verify the repositories and PyPI package can be archived as specified by the checklist.