Force designer to read from projects on server on command

[PGriffith]

[IGN-1655]Force to reload the file page-config/config.json after editing it from disk

May's still 'early', right? 8.1.28 will add the system.project.scan method noted above, in the gateway scope. There's also an SDK-accessible requestScan method that returns a CompletableFuture on ProjectManagerBase if you want to do anything interesting from a custom module.