Editor: Add WordPress.com integrations to the block editor

[mmtr]

Fixes Automattic/wp-calypso#32044.
Background: p3fqKv-6Hh-p2.

Changes proposed in this Pull Request:

Load the scripts of the WordPress.com block editor integrations that enhances the block editor with the features available in WordPress.com sites

Calypso Iframed block editor:

• URL is updated with the draft ID when the post is saved.
• Trashing a post redirects to the list of trashed posts in Calypso displaying a success notification.
• Revisions are managed with the Calypso revisions modal.
• Reblogging a post from the Calypso reader creates a post in Calypso with the except title and content.
• Media items are managed with the Calypso media modal.
• Posts are previewed with the Calypso preview modal.
• Back button on the header ("View posts") redirects to the list of posts in Calypso.
• Media items inserted in classic blocks are managed with the Calypso media modal.

WP Admin block editor (also included in the iframed block editor):

• Support for the underline and justified text formats.

Testing instructions:

• Start Calypso locally using the update/me-sites-version branch (Sites: Bump /me/sites API version to 1.3. wp-calypso#32527).
• Go to /block-editor/post/:yourJetpackDomain.
• Verify all the integrations listed above work as expected.
• Load :yourJetpackDomain/wp-admin/post-new.php.
• Check the underline and justified text formats are available on the paragraph blocks.

Proposed changelog entry for your changes:

I guess it's not needed?

[jeherve]

Quick first pass.

[jeherve]

Looks like this needs a rebase now.

[obenland]

@jeherve Could you give this another look when you get a chance?

[kwight]

Note that this should be rebased again and approved after #11354 is merged (it was based on #11354 for easier testing).

[jetpackbot]

Thank you for the great PR description!

When this PR is ready for review, please apply the [Status] Needs Review label. If you are an a11n, please have someone from your team review the code if possible. The Jetpack team will also review this PR and merge it to be included in the next Jetpack release.

Scheduled Jetpack release: May 7, 2019.
Scheduled code freeze: April 30, 2019

Generated by 🚫 dangerJS against 59c52ce

[mmtr]

Everything seemed to work, but I could see quite a few JavaScript errors in the Calypso editor, and some in the wp-admin editor as well:

Those may not be related to this PR though.

Thanks for testing! I can see the same errors while testing the WP Admin block editor on Jetpack master. The Calypso JS errors are also present on my local environment while testing other WordPress.com sites. So definitely not related to this PR

[jeherve]

Looking good now, although I think this could benefit from a rebase, some of those commits should not be here.