Inconsistent casing in GitHub repo connection state keys

Using `!hookshot github repo ` lower-cases the repo's path when saving it as the room state key, but using the provisioning API does not.

This causes problems because room state keys are case-sensitive, meaning that adding a repo via the bot command vs the provisioning API will add that repo to the room twice.

Besides, a repo's URL path should never be lower-cased, as GitHub URLs / repo names are case-sensitive: https://docs.github.com/en/repositories/creating-and-managing-repositories/troubleshooting-cloning-errors#ensure-the-remote-is-correct