Create unit tests to ensure endpoints work as intended

[WhaleJ84]

As of yet, all additions to the handler have been tested manually on a local instance of LibreNMS.
No unit tests exist for the handler, as I have no knowledge how to create a GitHub action that builds a LibreNMS instance with demo data for testing.
If anyone reading this can do this, point me in the right direction, or just help in anyway, please let me know!