Media & Text - Loses upload status if post is closed/reopened during the upload

[pinarol]

Detected during testing #1503.
Also reproducible @ 9f4afd6 develop
Tested with iPhone 8 plus, iOS 13.1

Reality:

• Add media & text block, tap placeholder and choose Choose from device
• Start upload but before it finishes close the post by selecting Update Post
• Re-open the post
• Upload progress is shown properly, but an empty white background is displayed under the progress view.
• Tap close(x), select Update Post
• Wait until upload is finished
• Re-open the post and see that media placeholder is shown back again

Expected:

• Add media & text block, tap placeholder and choose Choose from device
• Start upload but before it finishes close the post by selecting Update Post
• Re-open the post
• Upload progress is shown properly
• A dimmed & low resolution copy of the uploaded image should be shown
• Wait until upload is finished
• Re-open the post
• We should see that the image is shown properly

[pinarol]

I also came across with this validation error with the scenario:

• Add media & text block, tap placeholder and choose Choose from device
• Start upload but before it finishes close the post by selecting Update Post
• Wait until the upload finishes
• Re-open the post and you'll see: