Cleaning up sheet abstraction to use Ant/flipper-plugin dialogs instead

Summary:
This diff cleans up order remaining dialogs, the ones involved in exporting to file or url. Includes some legacy component cleanup boyscouting, but not too much.

This removes a lot of code where state of the wizard was stored globally, and makes it locally instead.

Other code that was removed involves interaction with the old UI, which allowed import / export to be running in the background as well. (which is no longer needed since we optimised the process)

Reviewed By: timur-valiev

Differential Revision: D30192000

fbshipit-source-id: 13be883c5bf217a3d58b610b78516359e9bd0ebc

desktop/flipper-plugin/src/ui/Dialog.tsx

@@ -237,6 +237,27 @@ export const Dialog = {
     });
   },
 
+  select<T>({
+    defaultValue,
+    renderer,
+    ...rest
+  }: {
+    defaultValue: T;
+    renderer: (
+      value: T,
+      onChange: (newValue: T) => void,
+      onCancel: () => void,
+    ) => React.ReactElement;
+  } & BaseDialogOptions): DialogResult<false | T> {
+    const handle = Dialog.show<T>({
+      ...rest,
+      defaultValue,
+      children: (currentValue, setValue): React.ReactElement =>
+        renderer(currentValue, setValue, () => handle.close()),
+    });
+    return handle;
+  },
+
   loading({
     title,
     message,