app.UseProxyHost being enabled means app.ExternalDomain sometimes
returns a domain/IP with a port attached. This is now removed, so the
refresh cookie is set correctly.
added "Use reverse-proxy reported "Host" when possible" option, which
will prefer using the "Host" or "X-Forwarded-Host" values instead of
"External jfa-go URL" in the web app. To do so, app.ExternalDomain/URI
are now functions which take *gin.Context (the latter optionally). The
protocol for the request is determined from X-Forwarded-Proto(col), so
make sure your proxy includes it.
The wiki will have been updated to mention the new option.
instead of just applying the cookie to the hostname you accessed jfa-go
on, it is applied to the one you set in jfa-go. The result is you'll
have to login twice if you access on localhost:8056 instead
of accounts.jellyf.in.
user-auth.go contains slightly adjusted versions of auth.go functions,
for authorizing jellyfin users (admin or not). Refactored auth.go so that
most code is shared. User auth isn't hooked up yet, nor has it been
tested.
