feat: add stdout and filesystem notification channels (#2925)

* feat: add filesystem and stdout notification channels

* configure through env vars

* compile

* feat: add compact option for debug notification channels

* fix channel mock generation

* avoid sensitive information in error message

Co-authored-by: Livio Amstutz <livio.a@gmail.com>

* add review improvements

Co-authored-by: Livio Amstutz <livio.a@gmail.com>

internal/notification/senders/debug.go

@@ -0,0 +1,46 @@
+package senders
+
+import (
+	"github.com/caos/zitadel/internal/config/systemdefaults"
+	"github.com/caos/zitadel/internal/notification/channels"
+	"github.com/caos/zitadel/internal/notification/channels/chat"
+	"github.com/caos/zitadel/internal/notification/channels/fs"
+	"github.com/caos/zitadel/internal/notification/channels/log"
+)
+
+func debugChannels(config systemdefaults.Notifications) (channels.NotificationChannel, error) {
+
+	var (
+		providers  []channels.NotificationChannel
+		enableChat bool
+	)
+
+	if config.Providers.Chat.Enabled != nil {
+		enableChat = *config.Providers.Chat.Enabled
+	} else {
+		// ensures backward compatible configuration
+		enableChat = config.DebugMode
+	}
+
+	if enableChat {
+		p, err := chat.InitChatChannel(config.Providers.Chat)
+		if err != nil {
+			return nil, err
+		}
+		providers = append(providers, p)
+	}
+
+	if config.Providers.FileSystem.Enabled {
+		p, err := fs.InitFSChannel(config.Providers.FileSystem)
+		if err != nil {
+			return nil, err
+		}
+		providers = append(providers, p)
+	}
+
+	if config.Providers.Log.Enabled {
+		providers = append(providers, log.InitStdoutChannel(config.Providers.Log))
+	}
+
+	return chainChannels(providers...), nil
+}