Make it so the filename is filled out by default when saving files

This was never ported from the Qt labs platform FileDialog, because
currentFile doesn't exist anymore. It's now called selectedFile.

(cherry picked from commit 31ef0a5223)

src/qml/FileDelegateContextMenu.qml

@@ -54,8 +54,8 @@ DelegateContextMenu {
             icon.name: "document-save"
             onTriggered: {
                 var dialog = saveAsDialog.createObject(QQC2.Overlay.overlay);
+                dialog.selectedFile = currentRoom.fileNameToDownload(eventId);
                 dialog.open();
-                dialog.currentFile = dialog.folder + "/" + currentRoom.fileNameToDownload(eventId);
             }
         },
         DelegateContextMenu.ReplyMessageAction {},

src/qml/NeochatMaximizeComponent.qml

@@ -110,8 +110,8 @@ Components.AlbumMaximizeComponent {
 
     onSaveItem: {
         var dialog = saveAsDialog.createObject(QQC2.Overlay.overlay);
+        dialog.selectedFile = currentRoom.fileNameToDownload(root.currentEventId);
         dialog.open();
-        dialog.currentFile = dialog.folder + "/" + currentRoom.fileNameToDownload(root.currentEventId);
     }
 
     Connections {

src/timeline/FileComponent.qml

@@ -72,8 +72,8 @@ ColumnLayout {
 
     function saveFileAs() {
         const dialog = fileDialog.createObject(QQC2.Overlay.overlay);
+        dialog.selectedFile = root.room.fileNameToDownload(root.eventId);
         dialog.open();
-        dialog.currentFile = dialog.folder + "/" + root.room.fileNameToDownload(root.eventId);
     }
 
     function openSavedFile() {