Include opengraph/twitter metadata on AMP Story posts

[westonruter]

See #9730.

Changes proposed in this Pull Request:

• In Allow plugins to add metadata to AMP Stories ampproject/amp-wp#2968 a new amp_story_head action was introduced for plugins to output additional page metadata on AMP Story posts. This action is functionally the same as wp_head and is analogous to the core embed_head action. This PR adds outputting of the jetpack_og_tags() on the amp_story post type which has a template which does the amp_story_head.
• Additionally, on any AMP response this PR suppresses the HTML comments added before/after the metadata tags since the AMP plugin will re-order the nodes in the head for optimal performance, thus the comments would no longer appear before/after the tags.

Is this a new feature or does it add/remove features to an existing part of Jetpack?

• Existing part of Jetpack: opengraph.

Testing instructions:

1. Do a build of the AMP plugin on the develop branch.
2. Activate the AMP plugin and enable the Stories experience
3. Enable the sharing module in Jetpack.
4. Try publishing a Story.
5. Verify that the expected meta tags are present:

7a8,23
> 	<meta property="og:type" content="article">
> 	<meta property="og:title" content="Bison">
> 	<meta property="og:url" content="https://wordpressdev.lndo.site/stories/bison-2/">
> 	<meta property="og:description" content="Bison">
> 	<meta property="article:published_time" content="2019-08-28T00:00:11+00:00">
> 	<meta property="article:modified_time" content="2019-09-03T18:01:03+00:00">
> 	<meta property="og:site_name" content="WordPressDevs">
> 	<meta property="og:image" content="https://wordpressdev.lndo.site/content/uploads/2019/08/American_bison_k5680-1-4.jpg">
> 	<meta property="og:image:width" content="1200">
> 	<meta property="og:image:height" content="783">
> 	<meta property="og:image:alt" content="Bizon!!">
> 	<meta property="og:locale" content="en_US">
> 	<meta name="twitter:text:title" content="Bison">
> 	<meta name="twitter:image" content="https://wordpressdev.lndo.site/content/uploads/2019/08/American_bison_k5680-1-4.jpg?w=640">
> 	<meta name="twitter:image:alt" content="Bizon!!">
> 	<meta name="twitter:card" content="summary_large_image">

Proposed changelog entry for your changes:

• Include opengraph metadata to AMP Story posts.

[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: October 1, 2019.
Scheduled code freeze: September 24, 2019

Generated by 🚫 dangerJS against 248914d

[jeherve]

Suggested change

	add_action( 'amp_story_head', array( $this, 'check_open_graph' ),1 );
	add_action( 'amp_story_head', array( $this, 'check_open_graph' ), 1 );

[westonruter]

Oops.

But I just realized that if this is applied, then the result would not be aligned:

		add_action( 'wp_head', array( $this, 'check_open_graph' ),       1 );
		add_action( 'amp_story_head', array( $this, 'check_open_graph' ), 1 );
		add_action( 'plugins_loaded', array( $this, 'check_twitter_tags' ),     999 );
		add_action( 'plugins_loaded', array( $this, 'check_rest_api_compat' ), 1000 );

So I just went ahead and removed the alignment: 2351a5a

[jeherve]

This should be okay short of a minor nitpick.

[matticbot]

Caution: This PR has changes that must be merged to WordPress.com
Hello westonruter! These changes need to be synced to WordPress.com - If you 're an a11n, please commandeer, review, and approve D32475-code before merging this PR. Thank you!

[jeherve]

Had to rebase. Still works well. Merging.