Use .fileImporter view modifier instead of DocumentPickerView

[rolson]

trafficstars

SwiftUI now has a way to import files without wrapping the UIDocumentPickerViewController: .fileImporter(...):

        .toolbar {
            ToolbarItem(placement: .topBarTrailing) {
                Button("Import File", systemImage: "folder") {
                    isShowingFileImporter = true
                }
                .labelStyle(.iconOnly)
                .fileImporter(
                    isPresented: $isShowingFileImporter,
                    allowedContentTypes: [...]
                ) { result in
                    switch result {
                    case .success(let fileURL):
                        ...
                    case .failure(let error):
                        ...
                    }
                }
            }
        }

cc @CalebRas