Enforce package name case sensitivity on some ecosystems

Some registries allow packages with different cases of the same name, others do not, we currently don't enforce that check on any registry to be on the safe side but it has created some duplicates that are incorrect.

There should be a flag stored on the registry which acts like a switch when looking up and syncing packages if it should be case senstive or not.

Start by locating the registry representation and the package lookup and sync paths mentioned in the issue. Determine how registry-specific case rules should be represented and exercised for both settings. Done means differently cased package names are handled according to each registry's rule without creating incorrect duplicates.

Written by the indexing model from the issue text.