[feature discussion] Document picker for saving / exporting documents

[edpizzi]

I needed a save / exporting document picker, corresponding to a call such as the following:

UIDocumentPickerViewController(forExporting: ["file://path/to/file.ext"], asCopy: false)

I have a simple change that provides that here:

https://github.com/edpizzi/ios_document_picker/compare/main...edpizzi:ios_document_picker:export-files?expand=1

It also adds support for an initial directory (which I'm hoping to use to open files in an iCloud container).

I could clean the change up to be merged (updating the example app, for instance) if you're open to it.

I felt the simplest path is to keep the pick and exportFile use cases as separate functions in Dart (to clarify which parameters each use case accepts), but keep them together in the plugin, since both paths are similar and share much of the same code.

[mgenware]

Hi, sounds good to me! Feel free to open a PR. I'll publish a new version. Thanks!