initializate client, server, shared

- initializated base structure of server
 - initializated base structure of client
 - initializated base structure of shared(lib for client and server)

server/test/server_test.dart

@@ -0,0 +1,8 @@
+import 'package:server/server.dart';
+import 'package:test/test.dart';
+
+void main() {
+  test('calculate', () {
+    expect(calculate(), 42);
+  });
+}