Add required scope when passing a Request Object

According to the [OpenID Connect Core 1.0 incorporating errata set 2](https://openid.net/specs/openid-connect-core-1_0.html) the client should pass the `scope=openid` parameter when sending the `request_uri` (e.g. after sending a PAR)

> Even if a scope parameter is present in the referenced Request Object, a scope parameter MUST always be passed using the OAuth 2.0 request syntax containing the openid scope value to indicate to the underlying OAuth 2.0 logic that this is an OpenID Connect request.

Author: gueuselambix

src/proto/request.c

@@ -128,6 +128,7 @@ static int oidc_proto_request_auth_push(request_rec *r, struct oidc_provider_t *
 	apr_table_clear(params);
 	apr_table_setn(params, OIDC_PROTO_CLIENT_ID, oidc_cfg_provider_client_id_get(provider));
 	apr_table_setn(params, OIDC_PROTO_REQUEST_URI, request_uri);
+	apr_table_setn(params, OIDC_PROTO_SCOPE, OIDC_PROTO_SCOPE_OPENID);
 	authorization_request =
 	    oidc_http_query_encoded_url(r, oidc_cfg_provider_authorization_endpoint_url_get(provider), params);
 	oidc_http_hdr_out_location_set(r, authorization_request);