fetchConfig function
Fetches from the backend without activating.
cacheExpiration null uses the configured minimum interval; Duration.zero
fetches unconditionally, which is a different thing and not the default.
Implementation
Future<void> fetchConfig({Duration? cacheExpiration}) => _awaitOutcome(
(port) => fdbRcFetch(cacheExpiration?.inSeconds ?? -1, port),
'fetchConfig',
);