[FIX] auth_oauth: google rejects nonce if response_type=token

I apparently missed this case in #88871: Google's legacy
flow (response_type=token) explicitly rejects a `nonce` parameter
being passed in the authentication request. The nonce parameter is
only accepted for an OIDC-conformant implicit flow request (aka
`response_type=token id_token`).

The specific endpoint doesn't seem to have any bearing on this, v1 and
v2 authentication endpoints result in the same behavior.

Drawback: Okta isn't supported anymore, as it requires the nonce, no
if, no but, even on "legacy" auth requests, possibly others. However
since these already weren't supported that's considered less of an
issue than possibly breaking compatibility with existing IDP.

Rejected alternative: adding `id_token` to the `response_type` to come
closer to OIDC-conformant request, however that was considered too
risky: Odoo clients could be using legacy IDP which also reject the
nonce parameter but don't have a magic "OIDC conformant" trigger.

closes odoo/odoo#91500

X-original-commit: 1fd738d9826f9bdfe8deddd5ef81dcb9757e8988
Signed-off-by: Xavier Morel (xmo) <xmo@odoo.com>
Signed-off-by: Olivier Dony <odo@odoo.com>

addons/auth_oauth/controllers/main.py

@@ -65,7 +65,7 @@ class OAuthLogin(Home):
                 redirect_uri=return_url,
                 scope=provider['scope'],
                 state=json.dumps(state),
-                nonce=base64.urlsafe_b64encode(os.urandom(16)),
+                # nonce=base64.urlsafe_b64encode(os.urandom(16)),
             )
             provider['auth_link'] = "%s?%s" % (provider['auth_endpoint'], werkzeug.urls.url_encode(params))
         return providers