User provisioning fails because app converts case in email address

In the dashboard user provisioning, we get the list of existing users from the app via SCIM. For users that were created via SCIM as well, we know the ID of the user as presented by the app. For users that were created by a different means -- typically on-the-fly by the app on first login, before the introduction of SCIM support -- we try to find the user in kratos matching by their email address.

That's all good, however, apparently at least Nextcloud returns the user's email address in the SCIM listing converted to lower case, so the matching fails. We'll need to do a case-insensitive matching to compensate for that.