refactor(MessagingService): umbenannt in SmsSender

EnvelopeGenerator.Application/Contracts/ISmsSender.cs

@@ -0,0 +1,11 @@
+using EnvelopeGenerator.Application.DTOs.Messaging;
+
+namespace EnvelopeGenerator.Application.Contracts;
+
+//TODO: move to DigitalData.Core
+public interface ISmsSender
+{
+    string ServiceProvider { get; }
+
+    Task<SmsResponse> SendSmsAsync(string recipient, string message);
+}