Add saving to and reading from a file

To make sure when our timer runs it runs

macos/Flutter/GeneratedPluginRegistrant.swift

@@ -5,6 +5,8 @@
 import FlutterMacOS
 import Foundation
 
+import path_provider_foundation
 
 func RegisterGeneratedPlugins(registry: FlutterPluginRegistry) {
+  PathProviderPlugin.register(with: registry.registrar(forPlugin: "PathProviderPlugin"))
 }