Improve Responsive Form Task reliability

We have made several changes that improve the reliability of Responsive Form Tasks with one or more File Upload Custom Fields, in adverse network conditions:

• We now submit all text Custom Fields before uploading files, so if the device has limited internet, file uploads do not delay the sync of that data.
• If an image upload fails (for example due to losing internet during upload, or limited internet causing it to time out), we will keep retrying until it succeeds.
• When your device is syncing recent offline updates to Payaca (for example when it has come back online, or limited internet is causing sync to take a while) we show a banner to make it clear to the user: