* fix: update the FileSelectHelper to support the new promise API
Fixes#18254
So it turns out we've successfully introduced a way to write
non-typesafe C++.
This fixes two things:
* Uses the object the promise resolves
* Ensures we attach the Then handler before moving the promise
* fix: also fix misuse of Promise::Then in the download manager
* feat: add method to DownloadItem that allows customization of dialog options
* docs: add docs for get/setSaveDialogOptions
* add missing copy constructor for DialogSettings on mac and linux
* fix: don't filter dialog options for mas build, don't return properties
* test: add test for get/setSaveDialogOptions
* fix: remove openDevtools added for debugging
* test: fix failing test because of new event parameter
* docs: use SaveDialogOptions instead of Object
