Added API for single notification dismissal (#2251)

* Added API backend for notification dismissal

* Added render statement

* Changed statement

app/controllers/api/v1/notifications_controller.rb

@@ -30,6 +30,11 @@ class Api::V1::NotificationsController < ApiController
     render_empty
   end
 
+  def dismiss
+    Notification.find_by!(account: current_account, id: params[:id]).destroy!
+    render_empty
+  end
+
   private
 
   def exclude_types