Allow user registration / signup through trusted header auth #808
Description
Describe the bug
pretty much the subject. when a new user that hadn't previously used wakapi is trying to log in via an oauth proxy, an "Unauthorized" error happens:
Reproduction
env:
...
WAKAPI_TRUSTED_HEADER_AUTH=true
WAKAPI_TRUSTED_HEADER_AUTH_KEY=X-Forwarded-Preferred-Username
$ curl wakapi.docker:3000 -H "X-Forwarded-Preferred-Username: teidesu"
<a href="/summary">Found</a>.
$ curl wakapi.docker:3000 -H "X-Forwarded-Preferred-Username: nonexistent"
<a href="/login">Found</a>.