Reverse logic of CreateCanonicalLinkAndUserIfNotExist() to first check if the user exists,
then create the canonical link. This allows seamless re-creation of users through SSO after
they have been deleted from Jellyfin but not properly de-linked.
Skip port number in redirect URLs during the following conditions
- The request scheme is http and request port is 80
- The request scheme is https and request port is 443
This creates redirect urls as https://server/path instead of https://server:443/path