chore: move the go code into a subfolder

apps/api/internal/notification/senders/chain.go

@@ -0,0 +1,28 @@
+package senders
+
+import "github.com/zitadel/zitadel/internal/notification/channels"
+
+var _ channels.NotificationChannel = (*Chain)(nil)
+
+type Chain struct {
+	channels []channels.NotificationChannel
+}
+
+func ChainChannels(channel ...channels.NotificationChannel) *Chain {
+	return &Chain{channels: channel}
+}
+
+// HandleMessage returns a non nil error from a provider immediately if any occurs
+// messages are sent to channels in the same order they were provided to ChainChannels()
+func (c *Chain) HandleMessage(message channels.Message) error {
+	for i := range c.channels {
+		if err := c.channels[i].HandleMessage(message); err != nil {
+			return err
+		}
+	}
+	return nil
+}
+
+func (c *Chain) Len() int {
+	return len(c.channels)
+}