[MM-53454] Add export file settings + slash command for public link (#23915)

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

server/channels/jobs/export_process/worker.go

@@ -19,8 +19,7 @@ const jobName = "ExportProcess"
 
 type AppIface interface {
 	configservice.ConfigService
-	WriteFile(fr io.Reader, path string) (int64, *model.AppError)
-	WriteFileContext(ctx context.Context, fr io.Reader, path string) (int64, *model.AppError)
+	WriteExportFileContext(ctx context.Context, fr io.Reader, path string) (int64, *model.AppError)
 	BulkExport(ctx request.CTX, writer io.Writer, outPath string, job *model.Job, opts model.BulkExportOpts) *model.AppError
 	Log() *mlog.Logger
 }
@@ -45,7 +44,7 @@ func MakeWorker(jobServer *jobs.JobServer, app AppIface) model.Worker {
 		rd, wr := io.Pipe()
 
 		go func() {
-			_, appErr := app.WriteFileContext(context.Background(), rd, filepath.Join(outPath, exportFilename))
+			_, appErr := app.WriteExportFileContext(context.Background(), rd, filepath.Join(outPath, exportFilename))
 			if appErr != nil {
 				// we close the reader here to prevent a deadlock when the bulk exporter tries to
 				// write into the pipe while app.WriteFile has already returned. The error will be