[MM-55726] Create batch report worker, add batch report job for exporting users to CSV (#25832)

* Split out migration logic and create generic BatchWorker

* WIP

* WIP

* POC batch reporting

* Oops

* Job hookup

* Working export to file

* PR feedback

* Merge'd

* Fix error handling

* Add API to start report, translations, couple fixes

* Add DMs to send reports to users

* Merge'd

* Update types

* A bit of cleanup

* Some fixes

* Add missing API doc

* PR feedback

* Fix generated

* Fix bug with post creation

* PR feedback

* Add some tests

* PR feedback

* Fix lint

* Some test changes

* Fix tests

* Add comment to explain why we forcibly stop

* Rework of some tests

* Batch report test

* Restrict batch exports to Pro and Enterprise licenses

* Fix erroneous comment

---------

Co-authored-by: Mattermost Build <build@mattermost.com>

server/public/model/post.go

@@ -52,6 +52,7 @@ const (
 	PostTypeMe                     = "me"
 	PostCustomTypePrefix           = "custom_"
 	PostTypeReminder               = "reminder"
+	PostTypeAdminReport            = "system_admin_report"
 
 	PostFileidsMaxRunes   = 300
 	PostFilenamesMaxRunes = 4000
@@ -450,7 +451,8 @@ func (o *Post) IsValid(maxPostSize int) *AppError {
 		PostTypeReminder,
 		PostTypeMe,
 		PostTypeWrangler,
-		PostTypeGMConvertedToChannel:
+		PostTypeGMConvertedToChannel,
+		PostTypeAdminReport:
 	default:
 		if !strings.HasPrefix(o.Type, PostCustomTypePrefix) {
 			return NewAppError("Post.IsValid", "model.post.is_valid.type.app_error", nil, "id="+o.Type, http.StatusBadRequest)