azuread securecookie: the value is too long

Nobody has claimed this yet.

Hi,

I cannot get azuread oauth working with goth. Has anyone managed to use azuread/azuread2?
The error:

> securecookie: the value is too long

Google sign in works fine.

The issue is with the size of the cookie being set in the browser.

I've tried using a postgresql session store.
```
store, err := pgstore.NewPGStore("postgres://postgres:postgres@"+os.Getenv("db_uri")+"/db?sslmode=disable", []byte(os.Getenv("SESSION_SECRET")))
if err != nil {
log.Fatalf(err.Error())
}
defer store.Close()
defer store.StopCleanup(store.Cleanup(time.Minute * 5))
gothic.Store = store // Appears to have no effect
```
This creates the session table but goth doesn't populate rows even on successful google sign ins.
I do not need the access token from the sign in. Only the verified email address.

Other issues mention removing claims/groups. This is with a new azure project with no modifications.

Thanks,
Simon

Start by tracing how goth/gothic.Store and the pgstore session store are used during Azure AD and Google sign-in, then compare the cookie data that reaches securecookie. Reproduce the Azure AD flow and inspect whether the session table is populated. Done means Azure AD sign-in can complete without an oversized cookie while retaining the verified email address.

Written by the indexing model from the issue text.