Taylor Madore

Rebased on main, added some validation to fetch_gomod_source, and added partial unit test coverage

Do we still need this? I believe we removed all of the other references to it. https://github.com/containerbuildsystem/cachito/blob/f626d97ea669e12879a72762e03aa92d862d66a6/cachito/web/static/api_v1.yaml#L1270-L1273