Add missing blocks origin to theme.json

[oandregal]

Trac ticket: https://core.trac.wordpress.org/ticket/56467
Backports WordPress/gutenberg#44363

This PR adds a missing origin to the code that processes theme.json. It also consolidates its name to blocks to be more reflective of what it affects. If the data coming from the blocks origin contained presets, it would be overriden by the data coming from the theme origin, which is not expected.

[michalczaplinski]

Hey @oandregal I don't really have the expertise to judge the code itself.

However, I am mostly just blindly following the testing instructions from WordPress/gutenberg#44363 and I can't reproduce the behaviour mentioned below:

Using a theme without theme.json (for example, Canape):

• Verify that the styles for the pullquote and navigation blocks are still present in the global-styles-inline-css. These blocks are the only ones that use the __experimentalStyle API in its block.json. It should look like this:

.wp-block-pullquote{font-size: 1.5em;line-height: 1.6;}
.wp-block-navigation a:where(:not(.wp-element-button)){color: inherit;} 

Here's a video of my issue:

2022-09-22_15-20-13.mp4

[oandregal]

Interesting, I've tested in trunk and it does not work either (it should).

It seems that we're missing a backport: I cannot find in trunk the filter *_theme_json_get_style_nodes, neither when it's thrown or when is used. This was introduced at WordPress/gutenberg#41160 and then the filter updated the name at WordPress/gutenberg#44189 Perhaps we're missing some backports?

[scruffian]

I think the reason it's not working is that this backport is missing: #3319

[hellofromtonya]

I started working on PR #3319 without realizing this PR is dependent upon that one. As they need to be committed together, I'm closing this one in favor of PR #3319 (as I've already made it a complete backport).