feat(storage): storage file structure changes (#3301)

- migrate persisted server data storage from `/gluetun/servers.json` to `/gluetun/servers/`
- add `STORAGE_SERVERS_ENABLED=on` to enable or disable on-disk server data storage
- add `STORAGE_SERVERS_DIRECTORY_PATH=/gluetun/servers` to configure where per-provider server files are stored
- keep backward compatibility with legacy `STORAGE_FILEPATH=/gluetun/servers.json`
- automatically read and migrate legacy `/gluetun/servers.json` into the new `/gluetun/servers/` layout when needed
- try to remove the legacy servers file after a successful migration to the new storage directory
- switch persisted server data from one large JSON file to a manifest plus per-provider JSON files
- add `UPDATER_PREFER_DIRECT_DOWNLOAD` to allow preferring direct download of provider server data
- keep deprecated updater flags `-enduser` and `-maintainer` as no-op warnings for backward compatibility
- preserve compatibility checks so persisted server data is discarded when its schema version no longer matches the built-in data
- allow preferred persisted provider data to override built-in data when versions match
- servers data now lives at https://github.com/qdm12/gluetun-servers/tree/main/pkg/servers

internal/cli/nooplogger.go

@@ -6,5 +6,7 @@ func newNoopLogger() *noopLogger {
 	return new(noopLogger)
 }
 
-func (l *noopLogger) Info(string) {}
-func (l *noopLogger) Warn(string) {}
+func (l *noopLogger) Info(string)          {}
+func (l *noopLogger) Infof(string, ...any) {}
+func (l *noopLogger) Warn(string)          {}
+func (l *noopLogger) Warnf(string, ...any) {}