Mono repo -> Master (#22553)

Combines the following repositories into one:

https://github.com/mattermost/mattermost-server
https://github.com/mattermost/mattermost-webapp
https://github.com/mattermost/focalboard
https://github.com/mattermost/mattermost-plugin-playbooks

server/channels/einterfaces/message_export.go

@@ -0,0 +1,15 @@
+// Copyright (c) 2015-present Mattermost, Inc. All Rights Reserved.
+// See LICENSE.txt for license information.
+
+package einterfaces
+
+import (
+	"context"
+
+	"github.com/mattermost/mattermost-server/v6/model"
+)
+
+type MessageExportInterface interface {
+	StartSynchronizeJob(ctx context.Context, exportFromTimestamp int64) (*model.Job, *model.AppError)
+	RunExport(format string, since int64, limit int) (int64, *model.AppError)
+}