feat: notification_message_controller

lib/controllers/notification_message_controller.ex

+defmodule NotificationDispatcher.Controller.NotificationMessageController do
+  alias NotificationDispatcher.Context.NotificationsContext
+
+  @doc """
+    Create can return {:ok, notification_message} or {:error, changeset}
+  """
+  def create(conn, params) do
+    case NotificationsContext.create_notification_message(params) do
+      {:ok, notification_message} ->
+        {:ok, notification_message, "{\"data\": {\"id\": \"#{notification_message.id}\"}}"}
+      {:error, changeset} ->
+        {:error, changeset}
+    end
+  end
+end
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