[RNMobile] Cover with in Cover support

[chipsnyder]

Fixes: wordpress-mobile/gutenberg-mobile#1739

Description

This PR implements the Cover block within a Cover Block for image uploads. Building off of #13909

This also modifies block parser for Image, Gallery, Media-Text, and Video blocks. (This was done in a separate commit so can be reverted to just Cover block if needed)

Related PRs:

• WordPress-iOS parent PR: Rnmobile/cover block uploads #13909
• gutenberg: [Mobile] Cover block uploads failure UI WordPress/gutenberg#21198
• gutenberg-mobile: Cover block uploads failure UI gutenberg-mobile#2150

To Test for Cover Block:

• Close post with an ongoing image upload from a cover block within a cover block )
• Close post with an ongoing image upload from replacing an image of a cover block that has a nested cover block
• Close/Re-open post with an ongoing image upload - steps
• Close post with an ongoing image upload - steps

To Test for other blocks:

• Image block - Close post with an ongoing image upload - steps
• Gallery block - Close post with an ongoing image upload - steps
• Media Text block - Close post with an ongoing image upload - steps
• Media Text block - Close post with an ongoing video upload - steps
• Video block - Close post with an ongoing video upload - steps

PR submission checklist:

• I have considered adding unit tests where possible.
• I have considered adding accessibility improvements for my changes.
• I have considered if this change warrants user-facing release notes and have added them to RELEASE-NOTES.txt if necessary.

[peril-wordpress-mobile]

You can trigger an installable build for these changes by visiting CircleCI here.

[peril-wordpress-mobile]

You can trigger optional UI/connected tests for these changes by visiting CircleCI here.

[mkevins]

Hi Chip 👋 😃 I tested this via the description, and it works as described. Also, I ran all unit tests, and everything is passing, and there is good test coverage for many nested cases 👍 .

I'll defer to @SergioEstevao for the code review, since he is very familiar with this area of the code, but the solution generally looks reasonable to me.

[SergioEstevao]

Working great!
Special Thanks for the updates on the Gutenberg block processor! We now are future proof for blocks inside blocks!