Remote
Construct a RemoteSettingsService
This is typically done early in the application-startup process.
This method performs no IO or network requests and is safe to run in a main thread that can't be blocked.
storage_dir is a directory to store SQLite files in -- one per collection. If the directory does not exist, it will be created when the storage is first used. Only the directory and the SQLite files will be created, any parent directories must already exist.