MM-23038: Compliance Report Fixes (#14242)

* add warning count as return value

* add warning count as return value

* fix file name

* update mock

* add setting warning to db

* replace wrongly removed string

* add dummy function to see if it will build

* remove dummy function

Co-authored-by: mattermod <mattermod@users.noreply.github.com>

einterfaces/message_export.go

@@ -11,5 +11,5 @@ import (
 
 type MessageExportInterface interface {
 	StartSynchronizeJob(ctx context.Context, exportFromTimestamp int64) (*model.Job, *model.AppError)
-	RunExport(format string, since int64) *model.AppError
+	RunExport(format string, since int64) (int64, *model.AppError)
 }