Update gutenberg bridge to support MediaInfo

[SergioEstevao]

Updates Gutenberg project and updates code to support MediaInfo struct to pass around media picker data.

To test:

• Start the app
• Create a new post using the block editor
• Add image and video blocks check that the different sources work correctly
• Try to copy one image from the photos app and paste inside a text block, check that an image block is added and you see an image upload simulation happening.

Update release notes:

• 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.

[etoledom]

Working great! Approved via wordpress-mobile/gutenberg-mobile#1494 (review)

Let's not merge this PR until we have the proper gutenberg v1.15.2 tag 👍

To solve the CI issue, it might help to delete the Pods/ folder and run rake dependencies again.

EDIT: I took the liberty to commit the Podfile.lock changes and the new gutenberg commit update.