Add macOS support (#23)

* Add macOS support

* Update README

* Update to v0.2.0

* Document breaking changes

* Delete widget tests

darwin/Classes/Utils/Constants.swift

@@ -0,0 +1,20 @@
+//
+//  Constants.swift
+//  nearby_service
+//
+//  Created by Kseniia Nikitina on 4/2/24.
+//
+
+import Foundation
+
+
+let SERVICE_TYPE = "mp-connection"
+let PEER_ID = "PEER-ID"
+let DEVICE_NAME = "DEVICE-NAME"
+let ON_MESSAGE_RECEIVED = Notification.Name("NearbySessionOnMessageReceived")
+let ON_RESOURCE_RECEIVED = Notification.Name("NearbySessionOnResourceReceived")
+
+let DART_COMMAND_MESSAGE_RECEIVED = "invoke_nearby_service_message_received"
+let DART_COMMAND_RESOURCES_RECEIVED = "invoke_nearby_service_resources_received"
+
+let ERROR_NO_INITIALIZATION = "NO_INITIALIZATION"