(Performance) Remove Task.Run from service layer and add new base async repository instead

[maniphanh]

• We need to remove Task.Run from service layer if repository doesn't return async since this is not going to help us in doing async but rather might hurt when we scale to multiple servers.

1. ClientService.cs
2. PhoneService.cs
3. UserService.cs

• To do a proper async we need to add new base abstract generic repository class with async CRUD operations
• Change all services to reference async repositories and bubble everything up to controllers