🛂(backend) match email if no existing user matches the sub

Some OIDC identity providers may provide a random value in the "sub"
field instead of an identifying ID. In this case, it may be a good
idea to fallback to matching the user on its email field.

CHANGELOG.md

@@ -25,6 +25,7 @@ and this project adheres to
 
 ## Fixed
 
+- 🛂(frontend) match email if no existing user matches the sub
 - 🐛(backend) gitlab oicd userinfo endpoint #232
 - 🛂(frontend) redirect to the OIDC when private doc and unauthentified #292
 - ♻️(backend) getting list of document versions available for a user #258