Preview Out-Of-Date if Save is In Progress

Expected behavior

A post preview should always represent the current content in the editor.

Actual behavior

If an autosave is in progress when the user attempts to preview the post, the currently-being-saved changes will not be uploaded and included in the preview.

Steps to reproduce the behavior

1. Open a very long post, ideally on a slow device (so it will be slow to save)
2. Add some content,
3. Wait at least 0.5 seconds (so the autosave delay has passed), but not much more than that (because we don't want the save to finish) and tap the "Preview" menu button.
4. Observe that the post is not uploaded (assuming there was no other updated content saved apart from what was added just before the preview was opened) and the preview does not include the just-added content.

Tested on Pixel 1, Android 11, WPAndroid 125b3984af