Check required WordPress version to set galleryWithImageBlocks flag

[derekblank]

Fixes WordPress/gutenberg#47782:

• Gallery block: Determine galleryWithImageBlocks prop value based on the WordPress version of the site when value is unknown WordPress/gutenberg#47782

The galleryWithImageBlocks param determines which version of the Gallery block should be used in the editor (v1 or v2). Gallery block v2 is supported in WordPress 5.9+ and should be used for all sites on WordPress 5.9 and above. This fix addresses an edge-case for self-hosted sites on WP 5.9+ that do not have the Gutenberg plugin installed. In this case, Gallery block v1 is the default, but Gallery block v2 should actually be used.

This code change checks the WordPress version and sets the param to true for any site using WP 5.9+, and keeps the original logic for sites not using WP 5.9+. Once WordPress 5.9 becomes the minimum supported version, this change can be removed.

An easy way to verify which version of the Gallery block is being used is to switch to HTML mode and check the tags in the markup:

Gallery block v2 syntax (figure + image):

<!-- wp:gallery {"linkTo":"none"} -->
<figure class="wp-block-gallery has-nested-images columns-default is-cropped">
    <!-- wp:image {"id":3326,"sizeSlug":"large","linkDestination":"none"} -->
    <figure class="wp-block-image size-large"><img
            src="https://****.files.wordpress.com/2022/05/image.jpg?w=1024" alt="" class="wp-image-3326" />
    </figure>
    <!-- /wp:image -->
</figure>
<!-- /wp:gallery -->

Gallery block v1 syntax (figure + ul + li + image):

<!-- wp:gallery {"ids":[38],"linkTo":"none"} -->
<figure class="wp-block-gallery columns-1 is-cropped">
    <ul class="blocks-gallery-grid">
        <li class="blocks-gallery-item">
            <figure><img src="http://localhost:8888/wp-content/uploads/2022/06/265-5000x5000-1-scaled.jpeg" data-id="38"
                    class="wp-image-38" /></figure>
        </li>
    </ul>
</figure>
<!-- /wp:gallery -->

To test:

1. Create a self-hosted site with WordPress version 5.9 or above.
2. Check that the Gutenberg plugin is not installed. If not, uninstall it.
3. Create a post.
4. Insert a Gallery block.
5. Observe that the Gallery block is using v2 (content is not rendered using inner blocks).

Bonus testing:

1. Create a self-hosted site with WordPress version 5.8 or below. (The WP Downgrade plugin can be used to quickly switch between WordPress versions.)
2. Repeat steps above and note that Gallery block v1 is used.

Alternatively, when running locally, the value of galleryWithImageBlocks can be logged in the editor to verify.

Regression Notes

1. Potential unintended areas of impact

• Block Editor Settings
• Gutenberg Editor Settings
• Experimental feature flags

2. What I did to test those areas of impact (or what existing automated tests I relied on)
   Manual testing

3. What automated tests I added (or what prevented me from doing so)
   Determined manual testing and CI checks would provide an adequate amount of testing coverage for this edge case.

PR submission checklist:

• I have completed the Regression Notes.
• I have considered adding unit tests for my changes.
• 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.

UI Changes testing checklist:
N/A

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	App Name	WordPress Alpha
	Configuration	Release-Alpha
	Build Number	pr20736-a9b862c
	Version	22.5
	Bundle ID	org.wordpress.alpha
	Commit	a9b862c
	App Center Build	WPiOS - One-Offs #5800

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	App Name	Jetpack Alpha
	Configuration	Release-Alpha
	Build Number	pr20736-a9b862c
	Version	22.5
	Bundle ID	com.jetpack.alpha
	Commit	a9b862c
	App Center Build	jetpack-installable-builds #4830

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[twstokes]

Thanks Derek for tackling this PR! 🚀

Results of my testing on a self-hosted site:

5.8 - trunk	5.9 - trunk	5.8 - this PR	5.9 - this PR

From my understanding of the difference between v1 and v2 Gallery blocks (thanks to this PR), this change appears to pass the tests in this PR. ✅

Comments / observations

• We should add an internal release note
• A bug label should be added as well as Posting/Editing
• A milestone should be added
• Consider adding expected output (e.g. what is shown in HTML mode). Readers outside of the Gutenberg world may not easily understand what inner blocks are or other differences between v1 and v2 (I struggled myself)
• The four items in the PR submission checklist should be checked before getting reviews
• Consider a note about what research you did regarding tests (since one isn't added)

Thanks!

[fluiddot]

I've tested different scenarios and confirmed the change works as expected 🎊 .

• WP 5.8.7 + Gutenberg plugin disabled => Gallery v1 ✅
• WP 5.8.7 + Gutenberg plugin 13.6.0 => Gallery v1 ✅
• WP 5.9 + Gutenberg plugin disabled => Gallery v2 (test case that this PR aims to fix) ✅
• WP 5.9 + Gutenberg plugin 13.6.0 => Gallery v2 ✅

NOTE: The latest version of the Gutenberg plugin that supports WP 5.8 is version 13.6.0 (The minimum supported WP version was set to 5.9 in Gutenberg plugin version 13.7).

[fluiddot]

LGTM 🎊 ! I re-tested what I did in the last review and confirmed this change works as expected ✅.

However, as I mentioned here, seems we still have an issue when using Gallery v1 and setting a caption that would be great to investigate.

[derekblank]

Thanks for reviewing @fluiddot! I've addressed the Caption issue separately here:

• [RNMobile] Fix Gallery v1 caption selector WordPress/gutenberg#51076